Hello ma'm,
You have pain related to tooth & gums might be because of dental decay .For exact diagnosis can you share clinical photograph of the teeth & area in question for better consultation ? Or you can visit dentist for further clinical examination & treatment accordingly.
It's not related to black fungus.
Next Steps
consult online through Practo for further information about it. or visit dentist for the same.
Health Tips
Don't worry about it. It has solution.
Thanks!