Ex Boyfriend Gaining Weight After Breakup?

Hi! So, I'm fourteen years old and I was "dating" a kid that I genuinely liked for a little over a month. We were not only dating, but very close friends. We were extremely honest with each other. I think it was cause we met shortly before we started dating- so there was no built up secrets already. But, about a month in out of the clear blue- he broke up with me. For about a week or two I was really upset about it, but now I've basically moved on. Unfortunately, I've noticed that he has since gained a LOT of weight. His reasoning for breaking up with me is unknown (but I believe he thought that I liked his best friend...which wasn't true in the slightest). My ex is fourteen as well. Anyways, he has had weight problems in the past as well as his entire family. He had recently lost a lot of weight right before we started dating. But in the course of about three weeks he looks to have gained like 20 lbs! I'm not sure if it's cause of our breakup because im not exactly 100% sure of his reasoning behind it. But it does worry me because even though he seems to hate me I do still care about him and his health. I'm not sure what I should do or how to feel or what to think. His weight was a huge topic of discussion between us because it's something he struggled with his whole life. I only see glimpses of him in the hallways because we have no classes together, but from what I've seen he has gained a tremendous amount of weight in a very short time. Penny for your thoughts? Thanks!