One of mine has a problem similar to yours. After multiple tests including allergy testing & biopsy she was found to be reactive/allergic to flies. Allergy shots didn't help at all even after a year, in fact they made her itch in winter too so I stopped them.
She now has to be on hydroxyzine every summer.
Someone on this forum mentioned ?magnesium? For skin problems. Can't remember the details but hopefully someone will chime in as I
D like to try something besides the drugs.
Good luck to you, it is frustrating.