What Causes Mild Pain In Rib Cage,hips And Arms?

For quite some time now (1.5 years or so) I have been experiencing mild pain along my rib cage on both sides (spreads into my hips, underarms and mid back at times also). The doctor has done multiple ultrasounds (including upper abdomen, complete abdomen, pelvic and internal pelvic) and blood work. Nothing has shown at this point. I do drive a lot for work so I am thinking that perhaps it is the amount of time I spend sitting in a bucket seat that is bothering me, but I am also concerned about the fact that the pain is spreading over time.