What Causes Bulging In Ribs And Space Between Ribs Under Breasts?

My ribs and the space in between my ribs are bulging under my breasts. I feel like there is something in the space in between my ribs. It looks bloated and I don't know what is causing it. I've had this for a few days now and it's scaring me. I am a 46 year old woman, 4 ft. 11 in., 109 lbs. I have IBS and ulcerative colitis. Iam taking Omeprazole, Librax and Asacol daily. What I am feeling is scaring me. I don't know what this is.