The usual treatment for mites is ivermectin ( ivomec ) as a spot on. However, you should really do a skin scrape if you cannot see the mites
It is just as likely to be ringworm, the treatment for that being Imaverol washes. ( you can use human athletes foot powder in an emergency as imaverol is not available over the counter as such )
To be honest without seeing it it’s impossible to diagnose and I’d suggest taking to your nearest proper carer or vet
Meanwhile you could use highly diluted tea tree oil on the area if the skin isn’t broken.
Be aware mites, mange and ringworm are all contagious to humans so make sure you take relevant precautions