stretch marks

Hey everyone, I'm 16 and have been on the pill for nearly 6 months. Recently I've gotten stretch marks on my boobs, butt and back that were never there before. I have no idea if this is to do with gaining weight, the pill, or just growing in general. I dont think there's anything wrong with them, but I personally don't like them on my body so is there anything you can do to get rid of them? Thanks, and why am I getting them?