What Causes Stiffness And Pain In Ribs?

Good morning, In feb 2012 I was diagnosed with ulcerative colitis-after colonoscopy of LT side.since then regularly I m taking mesacol,now there is no bleeding is there and regular mesacol BD u 800mg is going on.but now for last few days middle part of body has stiffness and mild pain in ribs and which keeps on shifting places. My Dr does not say anything but body feels stiffness kindly advise. Also pls advise can I take liv52 and pentocid L or not?