1 what may cause sudden pain in the ribs below the breast (right side)? It feels like a bruise but I know I have hurt myself. Sometimes the same kind of pain occurs in different parts of the legs. 2. What might cause sudden shaking/tremor in the hands? I never had this before. 3. I also feel the inside of my chest beating rapidly quite often and sometimes feel shortness like my heart is skipping a beat and I am forced to cough to get rid of it.