Could also be Mucocistis, infection, other oral changes from chemo. Chemo has just about the same side effects as radiation does. Mine were worse than radiation with high dose Taxotere, Cisplatin, and 5-FU starting after completing one week of TPF Induction chemo, which eventually required the hospital burn unit to debride the inside of my mouth, face, hands. 5-FU is also known to cause hand and foot syndrome, so watch that too. Whatever ailment it is always tell the oncologist.
Good luck.