Thanks for your query at DoctorSpring. I can understand your concern.
You are suffering from frictional dermatitis which is combined with slight infection of the skin which is caused by the humidity caused by the friction.
The best treatment for it would be application of a steroid antibiotic combination cream like hydrocortisone and neosporin cream, also mix it with clotrimazole cream. This would resolve the rash effectively. You can take an anti histaminic tablet like loratidine to reduce the inflammation due to the dermatitis.
Please let me know if you have any queries.