I would guess it's gas or bloating issues. Sometimes when we have a lot of air in our stomachs, it's more noticeable when we lay down. Just to be safe and to have a correct diagnosis, it wouldn't hurt to call and ask your doctor. Also, www.webmd.com has a lot of good information on different health issues. You might be able to get some idea of what's going on from there. Good luck and best wishes. Don't ignore this problem if it gets worse. It's best to be safe rather than sorry.