So my husband and i still have sex and its pretty much the same as when i wasnt pregnant. But now every time in on top and riding him my lower abdomen start to get really sore as if ive done 1,000 sit ups and almosy like ive pulled a muscle somethimes. Any idea what this could be? Should i be worried and stop sex? Also it goes away as soon as i stop grinding or when i stop moving. Im 27 weeks