What Causes Pain In The Ovaries After Stopping Birth Control Pills?

You asked: I stopped my birth control pill 3 weeks ago and since last week, I've been having this pain in my ovaries. I went to the doctor who did a scan and thought I was pregnant (we saw a circle/egg shaped image in the uterus), but the pregnancy test was negative. He said my uterus lining is thick and it seems like the egg will be released for me to get my period. I'm taking pain killers for the pain and just wanted to know if the doctors answer could be correct or could something serious be the problem, cause I'm still having this pain and it seems to get worse. Thank you.