What Causes Stomach Bloating And Pelvic Pain?

I have really bloated stomach that seems to move around like a lop sided ball when i lean back or from side to side. It looks like im pregnant and i have lots of gas. Bit of pelvic pain when pressing on the area. I had a baby 2 years ago by c section & am currently trying for another baby but am not pregnant yet. Its worrying me what it is.... is it just my stomach muscles moving around? Im quite slim so its really noticeable. help!