The neuropathy of oxaliplatin, as I understand from the literature and my own experience, is pretty much confined to the hands and feet. Pain in the ribcage is not typical of oxaliplatin neuropathy pain. Xeloda affects ths skin of the hands and feet - as well as mouth sores - and I don't see that causing ribcage pain.
I'd ask my doctor about the ribcage discomfort - it could have nothing to do with your chemotherapy side effects.
Good luck to you!