I have red blotchy rash, hot to touch, worse around joints under arms, kindly suggest

red blotchy rash, hot to touch, worse around joints , under arms near armpits and wrists, inner thighs, tops and sides of feet About once a year, usually in the spring, I get an allergic-like rash. Hot, itchy patches of small bumps that are worse around my joints. Rash is on tops and sides of feet. Ankles. Knees and behind knees. Inner thighs up to groin area. Outer thighs. Buttocks . Under side of arms and wrists. Nothing on my torso , not belly or back. Benedryl has not worked. Cool air feels good. The shower makes me itch. Moving makes me itch. There are moments when I really want to scratch it until i almost bleed. Not sure if it s food related or environment. No med changes. No unusual foods. No change in soaps or lotion or deodorant. Help!!! Kelly RN