Stomach discomfort

Does anyone else get stomach pain when you wake up on your back ? .. Ive noticed that since I been like 10 weeks..I'm currently 15 weeks and it just happened this morning ..its usually relieved by having a bowel movement..I sleep on my right side and if I wake up on my back I get like stomach pressure.. Like it feels like you have to go really bad.. But however if I don't wake up on my back I feel fine ..? Anyone else ?