Stomach hurts when laying down

So I’ve been having some stomach pain. I’m about 8 months PP. It just occurred to me yesterday that I was supposed to go back if I couldn’t lie on my stomach. Well I sleep on my stomach sometimes but it’s very uncomfortable. I went to the hospital had an US. I had blood work. They said it’s not an infection. I’m just at a loss of what it could be. I did have my organs completely removed because they couldnt see the baby she was on the smaller side. If this has happened to you can you explain what is was or if your experiencing pain what kind.