I Keep Having A Pain On My Left Side, Kind

I keep having a pain on my left side, kind of like a stitch when you get when running, but it's about as wide as a baseball, and not so intense. Yet has persisted for a few weeks now. It's not always there. Has been coming more regularly and I can feel it when I lean a certain way or like today, was stronger especially when I was walking. I don't know how to describe it exactly, when I walk it feels like it Jiggles, like a water balloon maybe.