I'm 18 weeks pregnant. I feel a hard mass on my lower right side that feels about 2 inches long, about 1/2 inch in width. It sometimes hurts. My ob. thinks it is "just a fibroid" & to get it checked out at my 20 wk. ultrasound. My sister had ovarian cancer that grew to the size of a basketball before any doctor started to worry. Is there any normal part of my anatomy that I would start feeling now?