I get spasm under my rib cage on the right side only. very painful. happens when i go to the bathroom and if i set wrong.

Myalgia/spasm: This is most likely involuntary muscle spasm related to movement and position. How long does your pain last? Is it related to moving your bowels? Do you have any recent injury or heavy lifting or bending? Try Myoflex cream and Advil (ibuprofen) for pain relief if you are not allergic.

SPASM: you are having spasm in the muscle between your ribs if recently you have been coughing or vomiting or straining you could bruise your ribs and the muscle between can go into spasm which is very painful use a heat pad and take ibuprofen and rest not better go and see your PCP