hi, as you mentioned your husband had cancer of mouth and was treated for it I will ask you if any chemo or radio therapy was performed. as during the stages of cancer there might be chances of inflammation of the cells which may irritate the nerve and lead to bells palsy. Now as your physician said, it could be returning , so for this I will say to undergo the test and rule out this factor. I hope and pray it don t come back and the pain is just a muscular. also a physical therapist will help improve the symptom of bells palsy and also by doing regular breathing exercises for a longer period will improve the oxygen carrying capacity of blood. Oxygen is the major form of enegry for cell Function and by increasing the levels of oxygen via breathing exercises will help the cells fight against cancer cells if present any in the body. There will be a massive detoxification of the cells. Also performing regular Cardiorespiratory body conditioning will help further. Along with medication , including breathing exercises and Cardiorespiratory training helps most of the time to patient and the body gets prepare to fight back. with the grace of God I pray that there is no chance of having cancer again and your husband to have peaceful pain free life.