Tinea Cruris. Local hygiene, it should be totally dry before wearing your clothes especially after taking bath, don't use undergarments in the night. As frequent travel, tight clothing for longer periods, application of combination of steriod cream,hot & humid envoinaments, obesity,diabetes  or any immunosuppressive therapies all aggravates the problem. Take an course of antifungal like tab.zimig(terbinafine) 250 mg once daily after food for 4 weeks, lulican (luliconazole)cream twice daily for 6 weeks continuously. Kz soap for cleaning. After 6 weeks use Abzorb dusting powder regularly twice daily before wearing clothes in the morning & after removing undergarments in the night. As a maintaince to prevent. Wash inner clothes regularly.