What could be wrong female cramps?

I been having cramps in stomach and back and I did pink tint to discharge but when went to hospital they couldn't find what is wrong with me. They said not pregnant, negative infection tests, and negative stds test. The doctor was concerned because my right ovary was lower than my left and there was a clear fluid in my cervix and surrounding my right ovary. No cysts ere seen oon stomach &d pelvic ulta sound. What could be wrong because I'm still in pain and debating going back to the hospital. Any ideas