Can be a fungal infection(mucormycosis), to start with we will need a culture test and might need a biopsy later.

Quit smoking

Quit smoking asap Need to get screening done for this patch Start :: Tab lycostar once daily for a month Apply gel Kenacort locally twice daily for a month

I am not increasing your worry, but most important at present to quit habits. With my experience it seems minor salivary gland inflammation.

Considering no H/O diabetic. Herpes zoster it can be. Maintain oral hygiene. Betadine mouth wash. Once a day after meal.  5-10 drops in mouth for 2 mins and spit out. Don't eat, drink or rinse mouth for next half an hour. Apply, hexigel ointment if asymptomatic. Or CNBC gel, if painful,, for 5-6 times/day. for 5 mins each time,do not swallow.

You should quit smoking, it may become worse due to the heat. Do not eat/ drink anything hot for few days. When possible get it examined to rule out pathology related to smoking.

This could be a ulceration of the palate, possibly by exposure to heat.