I am in the same boat. Had 3 Negative tests but the white tongue persists. Had it nearly 3 months now. It came on 10 days post exposure.
What did you guys do/find out?
Omg there are so many people with this problem, the doctors have done a lot of blood test and all negative. Im so down and desperate. Mine was after having unprotected sex with a woman that weeks after I noticed her tongue was like I have mine now. I remember at the time I looked at my tongue and it was so healthy ! It was pink, almost red. and never before I had a dry mouth. I regret it so much . Pls if you find what the problem is pls share, there are a lot of people like us with the same problem. We are all down and desperate.