Hi doctor my 1 year old son has sores in his mouth, he can't eat nor drink his formula he only wants water. please help?

It happens: I find that ice chips or chilled applesauce is a way to get something into them. You can also mix diphenhydramine (benedryl) in an equal mix with milk of magnesia & make a swish & swallow coating that numbs the sores. 1 tsp of the mix every 2-3 hrs. A slurry of chilled peaches or pears can also provide some nutrients. Avoid acid juices or salty foods.