I get this same rash on my in spots from the top of my ribs down to my lower hips, lower back, and buttocks. Once they appear, takes forever to go away. My primary dr thought it was heat rash but I get it the winter too. I don't think it's from dryness. I have diabetic polyneuropathy and small fiber neuropathy legs, feet, even in my hands somewhat arms. Have wondered if it's related to neuropathy because I didn't have a skin condition till the neuropathy started. Dr doesn't thing it's psoriasis. Caused by inflamation.