It can be many things that can cause this condition...ototoxicity, mostly from medications, and tinnitus, including radiation, and it could be referred pain from other structures on the face that share the same ear nerves, from the surgery, an infection, TMJ, growth of the existing tumor or new one, so these will probably be ruled out. If it is chemo related, other than switching to Carboplatin, which has less hearing toxicities, they may slow the rate of the cisplation infusion and give a lesser doses, maybe even weekly. It's good your husbad is going to see the ENTwho can best deal with this.

Good luck tomorrow.