Generally, unless you caught it really early, mouth rot needs to be cleaned out well, flushed and the chameleon put on an appropriate antibiotic to kill 5e bacteria involved. The most common bacteria involved is pseudomonas aeruginosa…it’s gram negative and very hard to get rid of. Chameleon pus is thick like cottage cheese and the antibiotics can not penetrate it…which is part of the reason the area needs to be cleaned/scraped out and flushed…with the chameleon under anesthetic.
A culture and sensitivity test can help with deciding the best antibiotic to use. The mouth rot could be playing a part in the tongue issue.