Hello~It sounds to me like you have a severe
Vitamin B
deficiency, this will
cause the tongue to look red and be sore, I know, it has happened to me. I suggested taking a good, high potency B vitamin, add to it, extra B-12 and B-1. Also, add some brewers yeast to your diet, this is chock full of B vitamins as well. I like to put a teaspoon on my cottage cheese or pop corn, it tastes yummy on pop corn actually.
Give this a try, it should get better in a few weeks to a month.