Horrible pelvic pain

About three weeks ago i ended up in the hospital for horrible pain In my right ovarie. They said they found no sign of a cyst just some fluid and blood in pelvic area on the ultra sound. The pain was there for about 5 days then went away. Two weeks later it came back same side same issue. The doctor did some test and I ended up to start my period which I haven't had one in about 2 months the pain was terrible again then once i started my period from the tests they did I had horrible cramping and side pain by ovaries on each side lower back pain they tested i am not pregnant and I had some weird clots come out. Saw a doctor said they saw on ultra sound maybe cyst in ovarie ovaries and also some loose tissue in my uterus. What can possibly be going on with my body i am exhausted and sick to tummy. It's finally starting to get better after a week of this pain and my period has stopped. I am on birth control as well.