Hello
Firstly have you been medically diagnosed with a fungal infection? If so here are a few precautions to take.
Avoid wearing sweaty/damp clothing. Wear light cotton clean clothes.
Keep the area clean and dry.
Do not share towels,clothes, toiletries. It is possible that you can keep getting the infection from people around you.
If anyone has an infection they must be treated simultaneously as well.
Complete the course of treatment exactly as advised till it clears fully.
Start with a course of
Terbinafine tablets 250mg once daily for 14 days.
Apply a terbinafine cream twice daily for atleast 3 weeks till it dries completely.
If it recurs show a doctor to check the lesion.
If you are not sure of the diagnosis do get it looked at to check for conditions like
eczema or
psoriasis on lower back. These require a totally different treatment.