You may be going down the wrong itch pathway entirely! You have focused quite a lot on the histamine pathway of itching as well as the whole candida/topical/what’s going on with the skin… but I hear nothing about the health of the nerves. If you are getting (and have gotten) that much sun exposure with tennis over the years, I am wondering about (but not actually diagnosing because this is an internet chat) neuropathic itch, which can be almost untreatable (sometimes). 1) become absolutely scrupulous with sun protection, do not step so much as a foot outside without being covered by UPF 50+ fabrics covering all of your itchy areas and any areas near your itchy areas! Sunscreen is insufficient as you will still receive UV radiation that will induce itching! 2) speak with your provider about medications to help with neuropathic itch- these medications are used for lots of different things and can sometimes have side effects like making people feel sleepy, so it is important to ask questions and talk through options for which option you are comfortable trying. 3) short application of ice packs can sometimes be helpful 4) capsaicin cream can sometimes be helpful, but talk to your provider first- especially since it is delicate skin on the forehead!

Good luck- do continue to use the sunscreen, but you have to shade that skin PLUS sunscreen- don’t let any UV rays touch that itchy skin ever. I have the same affliction on my arms… it is just the worst. Every couple of summers I think “maybe it’s gone away… probably a little sun exposure won’t hurt, right?” And I spend agonizing days trying to not scratch my own arms open into bleeding, scabbed messes until the itching, burning nerves calm down. It is the only itch that feels WORSE after scratching!