What could cause a feeling of a burnt tongue (without burning it on a drink) and metallic taste in mouth? any recommended treatment that does not require a doctors appt?

Unsure: However, there have been anecdotal reports of some people developing metallic taste with COVID 19. REF: https://www.refinery29.com/en-us/2020/04/9756359/metallic-taste-in-mouth-covid

Tongue/taste: You are asking for treatment without knowing cause of your symptoms (burnt tongue/metalic taste). Causes can include allergy, acid reflux, neurologic disorder, gum disease, neoplasm, etc. Best advice, go see your General Dentist and General Physician to begin the diagnostic process.

See below: Vitamin B deficiency can result in the symptom you have. Take any multivitamin available over the counter. If that does not resolve it 7-10 days, it would be prudent to see a doctor. Have a healthy diet, exercise 30 minutes/day, drink plenty of water, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/. Get HPV vaccine. Wish you good health!