Was your father diagnosed with oral cancer?

Almost everyone who goes thru radiation treatments for oral cancer will get mouth sores also known as mucositis. Radiation burns the sensitive mouth tissue. This can take many weeks to heal. Your fatehr should be rinsing his mouth several times per day with a mixture of 16 oz warm water, 2 tsp baking soda and 2 tsp salt. If the salt burns too much, omit it or better yet cut it back to 1 tsp. Salt water will help to heal the mouth sores so try really hard to get him to tolerate some salt in the mixture. Also he can ask for magic mouthwash which will help to numb his mouth long enough for him to eat. It doesnt last very long (20-30 minutes) but it will give him some relief.

Being your father is diabetic, make sure you check everything with his doctors. There are nutritional drinks like ensure, boost and some other brands that have special formulas for diabetic patients. Sorry but I am unsure what each specific brand carries.