entire stomach is tight constantly with no relief

Heather
26 weeks 1 day. Since middle of the night my entire stomach hurts and is so tight. Constantly - no relief. I thought it was gas. Tried walking etc. it's awful. Not like sharp. Just very full and tight and pressure. 
Anyone else ??? It can't b Braxton hicks bc it doesn't go away and come back it's there all the time.