I ve had a white coating on my tongue that tastes chalky when I scrape it off for 2 months at least. I ve been through all the tests and have been told that the culture result shows definitively no sign of yeast or strep bacteria, both respiratory and oral smear. I went it after noticing my breath was not good. I have a PDA so I have very strict oral health. I was on antibiotics for many years, 100mg Doxycycline 2x daily for acne. The initial thought was thrush. It is not the case. My boyfriend now has it, he developed it about 2 days after the bad breath. The white does scrape off and looks a bit like shaggy white carpet.
Thanks for your query, I have gone through your query. The white chalky coating on the tongue can be because of the food debris, or it can be because of hyperplasia of the papillae. Nothing to be panic consult an oral physician and get it evaluated to rule out hairy leukoplakia. The bad breath can be because of the gum infection secondary to deposits, or it can be because of the food lodgment secondary to decay, or it can also occur in respiratory or gastrointestinal tract diseases. Consult an oral physician and get all this thing ruled out, get your teeth cleaned and use mouth wash like chlorhexidine. Once the cause is found out consult respective physician and get it treated. I hope my answer will help you, take care.