My husband had pretty much the same treatment and started getting mouth sores after the first round of induction chemo (cisplatin, taxotere, and 5fu). He had oxycodone for pain at first but pretty quickly began the fentanyl patches Gary mentioned above and they worked well (then could use the oxycodone for break through pain). He began rinsing his mouth with baking soda and salt mixture multiple times a day and tried other mouth rinses as well. His second round of the three chemo drugs actually was easier than the first round because he began all of the rinses and fentanyl.