Get a blood test to see what you are allergic too. Meanwhile you might
want to cut raw beets out of your diet

Also - sometimes nutritionally deficient individuals have painful
tongues like that with certain foods. See if the feeling goes when you
stop eating the beets and if it doesn't, get a tibc blood test to see
if your iron stores are low and a cbc blood test to see if you might
have an infection (oncoming thrush, etc)

Hope this help any!