I concur. It could be endometriosis, which causes pain in weird spots. It could've been a uterine infection. It could've been a lot of different things, all of which you have to go in from that angle.
How old are you, Cindy? I think you've said that you have older teenagers, so perhaps it's an age related thing too. (As you know, women over 30ish have to be more careful about their reproductive systems.)
I'd go back to my own personal doctor, and talk to him/her.