I am soooo glad that this happens to someone else !!! It happens to me all the time. I say it is like my tongue is having a seizure! My tongue turns grey, numb and I am unable to talk until "it's" over. Seems to happen after a rapid movement...like leaving a restaurant, by the time I get in the car, my tongue is grey & numb. In the course of 1 day, this happens about 4-5 times. I asked my chemo dr. he said "ask your ENT dr. Well, at least I'm not alone..even if nobody else knows what this is...I'm glad YOU do!!!