Why am I having upper left abdominal pain that radiates into my left shoulder and left mid back ?
Sounds almost like what's happening to me.  Started off with abdominal discomfort for a few weeks, then suddenly I started getting back pain.  I've been to a couple doctors, and neither of them think It's anything serious.  Thanks, docs...you don't have to live in this body!  ;) Luckily I have a CT scan coming up...but I have to wait three weeks to get it. Could be anything from muscle strain, an ulcer, swollen spleen, kidney stone...there are lots of things it could be.  You didn't state your age or many other details, so this is a generality based on my existing research.