You can try a anti-itch cream that has hydrocortisone combined with a jock itch cream(anti-fungal cream). That combo seemed to work well for me. I did try rubbing some clay on it but that seemed to only stop the itching but did not help heal the infection.
I havent tried lavender oil or tea tree oil. Heat seems to aggravate rashes. I dont take a hot bath until the rash is under control.