Sounds like heat rash. I too work outside in a hot climate and the chafing and subsequent rash can be very painful. almost to painful to walk. I would try some O/C Hydro cortisone cream to try and reduce the inflammation. Then I suggest you use a product called Body Glide. It eliminates chafing and blisters. It comes in an easy to apply stick like a deodorant would. It is not sticky or messy. It is used by runners on any area that might chafe or blister including the groin, feet, or even the nipple area. It is usually available at running or sporting good stores. It is only about 6- 10 bucks and applying it daily 1 stick lasts a month. It has worked wonders for me, good luck.
This seems to be a fungal infection of the area called Tinea or jock's itch.Tinea cruris is the scientific name for fungal infection of the groin region.
It causes itching or a burning sensation in the groin area, thigh skin folds, or anus. It may involve the inner thighs and genital areas. Affected areas may appear red, tan, or brown, with flaking, rippling, peeling, or cracking skin.
The rash appears as raised red plaques (platelike areas) and scaly patches with sharply defined borders that may blister and ooze.
A warm, damp environment allowing the fungus to cultivate greatly contributes; especially with tight, sweaty or rubbing clothing.
Treatment is application of antifungal creams containing tolnaftate, clotrimazole or miconazole on the affected areas.
Newer agents such as butenafine are also used. If the skin inflammation causes discomfort and itching, glucocorticoid steroids may be combined with the anti-fungal drug to help prevent further irritation due to the patient scratching the area. However steroids alone are not advocated as they will worsen the condition.
To cure the infection naturally, keep moist and warm areas of the body clean and dry. Powders with menthol or zinc oxide may be used, like Gold Bond medicated powder, to soothe the itch.