ovarian pains

I've been having pelvic dull pain in my left ovary the last couple weeks. Everytime I have sex, it's very painful when he goes in real deep. My gyneocologist appt is tomorrow, but I'm so worried it might be cancer or something else really bad. I've also just started having diarreaha today. Also every since I started having sex, I get mild pains where my ovaries are. It only last for a day or so. I've talked to other women and they say it's normal. Since I started having sex, I've had a pap smear, so I know everything is normal because of that. But I never mentioned it to my doctor. What could cause that pain too?