I agree with CalGal about the Gallbladder, I would also have a GOOD physical workup on heart and lungs. If all of this is fine then start on the Muscles, do you have muscle spasms, pain anywhere else? this could be an indicator of low potassium or magnessium if a muscle issue, etc. Good physical, with blood work and UA is a great place to start. Write down ALL of your symptoms, even the seemingly minor ones. Good luck
You may want to consider having your gallbladder checked.