Possible things,Center of chest. Heartburn or costocontritis. Heartburn, see if an antacid helps it. Magnesium based if you are constipated, Calcium based if you tend to diarrhea.Costcondritis tends to be more consistent, if you can tolerate NSAIDS try one of those (some IBSers cannot) or tylenol. It is just the joints in the ribs being irritated, kinda like tendon problems anywhere else other than it is hard to stay off your lungs and not use them for a week or two where you can rest an arm or a leg.There are bends in the colon under the ribs on the left and right and those often cause pain in IBS Short term, try peppermint or an antispasmodic. If you can predict when they happen or they happen every day do the peppermint/antispasmodic regularly or try taking it before the pain (like if it always happens after meals, take them 20 minutes before a meal).Longer term as sometimes it is gas getting trapped there try a lower starch/lower carb diet or probiotics.
