Kammerflage Kreations had a chameleon turn all white in a similar fashion. It only lasted for a period of time before the colors returned. Hopefully, yours will do the same.
I've had similar experiences with one of mine. I think mine had a short lived vitamin deficiency (Vit A). I supplemented two days in a row with a multivitamin and his tongue returned to normal.
It could be a tongue strain or injury. In this case I would suggest just waiting a week or so and...