Rash:red, blotchy, not raised/itchy/painful/spreading, cortizone/antihistamine didn't help. Not in skin crevice-front/side of knee, one area for 2 months

NOT.... Do you mean that they are not raised/itchy/painful/spreading? May just be dry skin and the redness from your rubbing. Try some moisturizer on the area after bathing for a week or so to see if it helps. But it does not and this does bother you, consult a dermatologist.