unfortunately I can relate all too well to this story. I had soft wavy hair as a child, but then when puberty started it went curly, so I went from having a 2a to a 3b or so in just a few years. I loved my curly hair and, once I learned to care for it, people used to stop me in the street and tell me how amazing it was. At 15 I was dx with epilepsy and put on Sodium valproate/Epilim, and then my hair started straightening out. I didn't realise it was the pills, so by 20 I had almost my childhood hair back- its like a 2b now. I tried quitting the pills a few years ago, but so far I haven't noticed any difference in my hair. I am hoping that proper products will fix it up again, because I am still depressed about losing my curls. I would definitely talk to your doctor about it, but do your own research too and see if you can find a pill that WON'T mess with your hair.
Good luck!!