Totally fine

Intense

The talk with Mrs Midoriya was... Intense. Tha lady was determined to know every little detail about her son's illness, and she kept asking Aizawa to allow her to come take the kid back home. He can't blame her, of course, he had seen first handedly how stubborn the problem child could be when hidding his sickness from others.
"Mrs Midoriya, your son is at the infirmary at the moment, taken care of by our very own Recovery girl. This is the best treatment he can get. I don't think it's wise for you to drive here that late and take him. He will rest for the night under the close supervision of a medical expert, and I will call you again in the morning and update you. Is that okay with you?"

The woman kept crying during the talk, a familiar trait. They agreed at last he will update her first thing in the morning, and Aizawa was relieved the phone call was over.
"She's quite a character, huh?" Aizawa tried to laugh with his colleague, but Yagi seemed out of it. "I wonder what happened to the kid's father" he tried to get the blonde to talk. "W-what did you say?" Yagi stuttered. "Are you by any chance Izuku's father?" said the homeroom teacher all of a sudden.
"What?! No! How did you get to that weird conclusion?" Toshinori was shocked by the comparison. "Well, the kid never talks about his father, and you dote on him like one... And the quirk thing..." Aizawa reasoned. "Mr Midoriya is overseas, that is why we don't have his contact number" Toshinori closed the conversation, turning to step out of the office. He really wanted to go back to the infirmary, but he knew both Aizawa and Recovery girl will be mad if they saw him there.

"Okay, okay. I guess we both should go to sleep soon, we have school tomorrow and I still need to check problem child in the morning and contact his mother" Aizawa said. "I-I can do that, if it's okay..." Yagi started to mutter, but his colleague put his hand in the air. "No, as his homeroom teacher this is my responsibility. Thank you for helping me with him today, but don't get used to it. You are not to visit the boy until I say you can". Yagi nodded with a sad face, going in the direction of the building's exit. Aizawa followed him out, and they both walked in silence toward the teachers' dorms.

"Are you going to tell the kids at class tomorrow?" Toshinori asked when they reached their dorms. "Yes, I need to update them as well... Well, good night All Might, I will see you tomorrow."
"Good night, Earaser".

Izuku woke up with a sneeze. His body ached and his head was pounding. He felt terrible. When he opened his eyes, Izuku saw a familiar ceiling, but not the ceiling of his dorm room, no. He was in the infirmary.
He tried sitting up, but the room spinned so fast all he could do was close his eyes and groan. He heard the tapping of small feet coming closer to him. "Hey kiddo, how do you feel?" the voice of Recovery girl was heard. "Great, totally fine" Izuku tried his best, but another sneeze crashed his chances of ever convincing her he didn't feel like shit.
"And if you don't lie, how do you feel?" she asked again. "Like I was Texas smashed in the face" Izuku responded weakly. He coughed a little, his eyes still closed, and it felt really bad in his chest.

"Let me check your temperature again, you look much better than before" chirped the small woman as she stood on her stool. She shoved a thermometer in Midoriya's mouth and measured his pulse while waiting for the beep. "Let's see, you've been here for 3 hours and you pulse got really better. About your fever..." beep. "Huh, much better. Only 40.0, you're on the right track, boy. Try to rest some more, I will come again in two more hours to give you another dose of the medicine".
"Thanks, Recovery girl" Izuku whispered, his voice raspy and broken. He sniffled a bit, feeling his nose running. "Ha...Choo!" Izuku sneezed so hard his body jerked, his nose nearly exploding. "Here, son. I put some tissues next to your bed, you should not sniffle like this, it will clog your sinuses" said the woman and left him be.

Midoriya took a tissue with his trembling hand, sneezing into it. He felt so congested, so exhausted, so BAD. Maybe going back to sleep would be a good idea. His nose kept running though, and he kept sneezing for some time. Izuku shivered under the light blanket, wishing he had his own warm and fluffy blanket on him. He was cold and hot at the same time, the feeling was aweful. After a few more minutes he dozed off, falling asleep once more.
More fever dreams came and went, but everytime Izuku woke up and saw the ceiling, realizing he was just dreaming.
When Recovery girl came back they both were really tired, so she just measured his temperature (39.9, progress!) and gave him another injection.

When morning came, Izuku heard the voice of his homeroom teacher. He opened his eyes slowly, the light hurting his head, and searched for his teacher with his eyes. Aizawa glared at him.
"Good morning problem child. How are you today? Don't dare lie to me, I can read you like a book". "I've been better..." admitted Midoriya between little coughs. Little, but painful indeed.
"Fever?" asked Aizawa, Recovery girl holding the thermometer in her hand. They fussed around him a bit, and then Aizawa turned to leave.
"Hey, sensei" Izuku tried to speak, his throat croaking, "did you take me here yesterday?". "Yeah, I tried taking you to the hospital, you had me worried there, but they wouldn't let you in" Aizawa responded. "T-thank you" Izuku mumbled. "You're welcom kid. Don't do it again, though" the teacher smiled and left.

"You can stay here for a few more hours, and then I'll send you back to your room. After lunch some second years will arrive injured from training" said Recovery girl, and Izuku coughed a little 'thank you' and fell asleep.
He woke up by a loud noise. It was Kacchan's voice, screaming something. Izuku opened one eye and saw his classmate's face near his own. "K-kacchan?" he asked with his congested voice. "Oi Deku, you still sick?" asked the explosive teen, concern in his voice. Izuku sneezed in response, using the crease of his elbow to shield Bakugo from the exploding snot rushing out of his nose. "Gross, shitty nerd. That sounded like a pool of germs" Katsuki commented, taking a few steps back from the ill teen.

Wiping his nose, the green haired glanced at his former best friend. Kacchan saw him sick before, when they were kids. He sould have known by now that Izuku was the sneezing type of sick people.
"What do you want?" Izuku asked coldly. "Er, I just wanted to check on you, you dumbass. You were f*cking dying yesterday or something!" Katsuki yelled and left the stunned Midoriya staring at him with wide eyes. Did Kacchan... Care? For him? Maybe he caught Izuku's fever or something...
Another loud sneeze brought him back to reality. He glanced at the clock on the wall, it was almost 8 AM.
'Great, I'll miss another day of classes. I'm gonna fall behind again' thought the green haired boy and sniffled. "Choo!". Izuku sighed and closed his eyes again. He really wanted this sickness to end already.