Is this different from geographic tongue? I didn't think that was supposed to hurt though. But I did see an article that said there was a connection to geographic tongue with dairy allergies.
I agree with Aldunn, you need to see a doctor or even a dentist. However, this also could be due to a lack of B vitamins, now, don't laugh, if you do not get enough of the B vitamins, one of the symptoms is a sore tongue, and if left untreated by not taking them, it can get worse. I would try taking a good, food grade B vitamin complex, also, get some Brewers yeast, it can be obtained at any health food store, this is chock full of all the B vitamins, amino acids and other important nutrients and minerals. It taste good too, I love it on cottage cheese.
I was always taught that this condition was caused by stress, anxiety and depression. There oral lidocaine that your doctor can prescribe that can you can use when your tongue hurts. It will numb it and lessen the pain. You should ask your doctor about this. If you are concerned about this condition, you need to see your doctor. I didnt see anything in your post where it said that you have been to the doctor.