I have a pain on the left side lower abdoman, about belt level, could this be my gall bladder acting up?

It sounds like it could be something related to your digestive system. It also could be any number of things like irritable bowel syndrome(IBS), diverticulitis-diverticulosis(related to the colon), colitis(colon-related), or something intestinal. I'm not trying to alarm you, it could also be gas, I do think you need to see a gastroentrologist(sic?).