U could have a tilted or low sitting uterus. Or cervical or ovarian cysts. I have ovarian cysts that rupture and when i mentioned pain during sex to my gyno, he said i might have endometriosis. I can only have intercourse without pain if i am on the bottom. I also get pink discharge or bleed after. You should post your question in the ovarian cysts forum, and endometriosis forum. Doesnt hurt to cover all bases. But your best bet is to contact your gyno and tell them whats going on, so they can find out why. Hope this helps.
this happened to me before, i had a cyst on my cervix, i needed it quarterised (a piece removed,) then allowed time for it to heal, now it's great during intercourse, doesn't hurt any more. see a doctor. good luck
If it hurts whilst you are not using the ring then it could well be that it is not the ring that is the problem.
If sex hurts then you should consult with your doctor. If sex hasn't hurt in the past then I think that you should get yourself checked out.
I'm no expert, but based on what you've said, I would draw the conclusion that it's possible the ring caused a bruise or rash inside your vagina that is being touched when you're in the wrong position.