Hello DR I Recently Acquired A Rash Under My Arm

Hello DR I recently acquired a rash under my arm pits and under my tricepts. As well as above my groin and around my upper thigh areas. Occasionally
I feel like sharp pins throughout my body not painful just brief pins feelings then passes. I have no allergies but feel like maybe its a heat rash as I live in the desert. Its not like shingles but I have had chix pox? No fever or any other symptoms just the red rash in these areas 3 days now.