some of the reasons you are feeling movement in the left side of your abdomen

These may be some of the reasons you are feeling movement in the left side of your abdomen. 

1.) Peristalsis: it's regulated movement of the bowel which pushes food downward. 

2.) Spasms: Bowels are muscular organs . A spasm is a involuntary sustained contraction. Your Dr. can prescribe you a anti-muscarinic drug to help this. 

3.) Subcutaneous emphysema: air trapped under the skin. It can feel like bubble wrap when the air shifts around. It can feel like rolling.

 I've experienced this myself. I'm not a Dr. , this is just some things that I came up with from doing my own research. Hope it will be a help for you !!