Movement in Lower Abdomen?

Hi,

So I'm having this weird movement in the lower part of my stomach it feels like something rolling gently and it doesn't just happen on one side it tends to go back and forth, its been happening for a few weeks now. And I know there's no possible chance that I could be pregnant?.. I'm on the implanon birth control and I've been on it for over a year now but I have had unprotected sex. Sometimes I also feel pain every once in a while and I've been very emotional lately with a little bit of a appetite change. Could someone please help me???