Pressure...

So at my check up yesterday my doctor had pushed down on my pubic area to see if baby girl was head down. Well she is and he also said that there's a possibility that she will not move from that position. Well tonight, I've been feeling TONS of pressure and a lot of cramping on the sides, kinda like my ovaries are throbbing and gonna explode. I had gone to the hospital on Sunday for bleeding and they checked my cervix and said that I'm 100% closed! Now I'm wondering if this is just my uterus growing even more since I am 31 weeks today, or if this is something I should be worried about?