Hardening in belly

My stomach keeps getting hard at the top of my uterus and its very uncomfortable. Whats going on? Contractions that high up? Walking dont help either. I drank some water and it easied off for about an hr but seems to be starting up again now that I am laying in bed. It makes me nauseous also and baby is going crazy in there. Dr checked a wk ago & said i was still closed. Im almost 38wks.