cat eating problems

My 11 year old male cat had advanced 4c resorptive lesions and received 4 crown amputations 2 1/2 months ago. 3 months prior to crown amps, he began having trouble eating with head turning and excessive licking and unfinished food. He handled more liquified, gravy based food better though after a while, he was simply licking up the gravy and leaving the solid food. Symptoms gradually worsened and were not resolved by crown amps. In fact, they progressed. My cat would now stop after only a spoonful of food and recoil in apparent discomfort or pain walking away with dramatic and excessive lip licking, jaw opening and closing, pawing at both sides of his face and a lot of general comfort licking. Dry food was better but not a solution as he will still only eat small amounts. CT scans and dental, chest and neck xrays all negative (CT shows deviated septum but no polyps). Surgical sites look well healed. No inflammation or infection. No ulcerations. No bad breath. History of constipation, sneezing and sensitive ears. 1 dose of Mercurius Corrosivus 200c was suggested by a sales person but concerned about possible irritation to gums and excessive salivation based on what I've read. Cat also does not have any of the signs associated with this remedy - other than the location of the problem ie mouth. First thought was treating possible nerve pain with Hypericum (dose unknown?). Looking for any helpful feedback and suggestions.
[message edited by courtofpublic9 on Mon, 30 Apr 2012 18:06:04 BST]