Hi Starlight,
Yes, IBS can make you have pains under the right hand side of your rib cage. I don't have much of that kind of pain anymore though.
My personal opinion is that it can be caused by an overactive gall bladder. Again I personally believe that if there is too much bile it can cause you to want to heave and feel full. Depending on whether you suffer from C or D variety IBS you can help yourself to some of the common cures for this problem. If you suffer from C you can use a quarter of a bile salts pill, which will simultaneously help the C, help reduce pain and will reduce your chest pains (I use the pills on the days i suffer from pain in the chest). If you suffer from D variety you can use bile absorbants which are not OTC (over the counter) such as Colestid or Questran.
Well, you can get a lot more advice from others on this board as well, as to how to handle your IBS.
Cheers,
Raju.