I went through something similar. One of the many doctors had suggested an absolutely no sugar diet, which is awful. I did it for a short term, just to check the box. I was down to leafy greens chicken and pork (with just herbs and spices). Lots if supplements. The purpose of the diet was to reduce the sugar to reduce the acid. I had an orange tongue about which I have posted. The most successful treatment was the Clotrimazole tabs followed by clorahexadine mouthwash applied to my tongue with Q-tips (2 weeks). I also use a metal tongue scraper twice a day. After 2 weeks of this regimen the orange tongue went away. I went through many treatments, diets and docs.
I have not looked at my tongue for weeks!