Undies for my son's growing butt

Growing Butt

Hello Everyone! I am Helen, mother of a 15 years old very obedient and good boy, James. Just we two live alone in our house.
Here's the story of the time when his butt started to grow huge slowly and slowly.
One day I noticed that my son, James (Jimmy) was adjusting pants again and again and having some trouble. When I asked, he told me that there's a little pain down there his waist. I immediately asked him to come to me and let me inspect. I felt like there is a very little swelling near my son's waist and butt area.
I love my son very much and I'm kinda overcaring mother. He was shy standing there in nothing but his boxers on but I inspected properly for swellings and areas where it was paining.

I was a little worried because the reason was unclear. But the pain was mild and everything was okay as of now, we didnt do anything for it today. For reference for the future, I brought a measuring tape from my cupboard and measured his waist and butt area as of today. It measured out to be 29inches and it looked normal as he was a skinny little cute boy even for his age. He was still adjusting his boxers now and then standing just in his boxers. And since his pyjamas were pretty loose and comfortable it was clear that the problem is with his undies, his boxers are giving him troubles. 

The next weekend, I took him to our regular shop where my friend Katie works. We told her to give us different sorts of underwears for him and told her about the increasing swelling and increasing pain.

She brought all sorts of undies but nothing solved the problem and only increased the mis-fitting problems. He tried different types and sizes of boxers and briefs.

Now it looked like a problem because he tried many but nothing was really helping reduce the discomfort and kept paining even more because of new tight fabric material.

Katie told me that there's only one way left. We have some soft fabric undies which will be comfortable and will fit Jimmy really well. Here you go, wear this and turn around let me take your new measurements. And tell us how are you feeling.

I looked at the new underwear that she gave to Jimmy and I was about to interrupt but stopped because she gave me promising words that it will be super comfortable to my dear son and the soft material wont hurt on his swelled butt. I thought Jimmy will recognize that they were actually PANTIES and will obviously refuse to wear them. But Katie smartly brought panties with nothing written on them and in black color. So Jimmy did not know that they were not any average boy's underwear but girl's panties! The most shocking thing was we could not believe that they were actually the solution to our problem. The panties were actually really soft and gentle on his swelled ass. He himself said that he liked them and was happy that they finally found undies that do not hurt his swelled butt anymore. 

Katie called me to side to talk to me about it.
She started to giggle and said that "I knew from the start - ass of this shape and size belongs to a young girl and not a young boy" I being a mother who loves her son was in shock. And I asked her what she means and told her that we cant buy girl's underwear for Jimmy.  Katie then told me simply that she obviously would not force us to buy panties and said that she know that it is not normal for a boy to buy and wear panties. She said that "But it is not normal case here, Jimmy himself said that he liked these undies and agreed that these are gentle on his swelled ass. He looks happy to found a perfect fit." I really love my son's comfort and had to agree that these panties were the solution to their weird problem. But I know that if we tell Jimmy that these are not boy's underwear and that these are panties, he will refuse to wear them right away and will stay in pain. So I thought the best way is not telling him for his own benefit and comfort.

So I agreed with Katie and we decided not to tell him that what he's wearing and buying are girls' underwears. When I saw the new measurements, I was shocked that it increased by 1 inch in just a week. Now it was 30 inches. I decided that we will just buy one or two panties for him and I will take him to doctor as soon as possible to get that swelling check and stop it. Then the problem will be solved I thought.

When I went to my Jimmy and was about to say that lets leave with just two undies, he insisted to buy more I had no choice but to listen to him because I can not let him be in pain. Katie was enjoying all of this and brought a large variety of panties for Jimmy. I was scared that he might notice but Katie was an expert in selling things and she tricked Jimmy into thinking all those were new fashion boys underwears. She brought some black and some gray plain panties and she wanted to go for more girly ones but I stopped her and took somewhat boyish looking panties and left the store with only some panties.