Abdominal pain

So a few days ago, my stomach started to feel like a bit crampy. Like I pulled a muscle or something. Now I’ve noticed that whenever I lay down, my stomach rumbles and I get waves of cramps from the belly button to under my rib cage and on the sides. When I sit up or stand up, I feel fine. I’ll still feel a bit of the cramping but it’s all bearable. I would rate the pain when laying down like a 4 or 5. My stool looks normal. I don’t feel nauseous. Havent thrown up. No fever or chills. No heartburn. Any ideas?