Hiya Lilly. I was diagnosed and had treatment for endometriosis in October. Mine was not dramatic but I always had very painful, heavy periods which even being on the pill didn't help and then I started having pain when having sex sometimes. I went to the gynacologist about something else cos the doctors had always just said it was just how my periods were. He suggested I have an small operation to get checked out, I did, and I have it. I had some bits of endometriosis removed and now I can have pain free sex again! YAY!! Also, at the age of 26, have had my first ever period where I didnt have to eat painkillers for 3 days solid.
Go and get checked out. If you go to your GP you may have to suggest endometriosis as in my experience it's not something they will think off (hopefully your gp will be more up on it than any of mine have been). It might be helpful to make a list of the symptoms you have cos when they are rushing to get to the next patient you might forget. If nessessary ask to be referred to a gynacologist. Its a very difficult disease to diagnose and the only sure way to diagnose it is to have a small operation called a laparoscopy.
Get yourself down to the doctor and good luck xxx