Constant Tightness in Belly

Does anyone else's belly feel constantly tight?  It's not contractions because it's ongoing not in intervals. I'm 33 w 4 d. I don't remember feeling like this with my first. My whole stomach just hurts and makes me feel sick at my stomach. I laid down this afternoon and it just hurt so bad I cried for half an hour. I've had it going on the past couple weeks for hours at a time. Today has just been the worst and it makes it extra hard to breath. Could it just be her position?  Has anyone else experienced this?