Have you spoken to a doctor about this? It sounds like a histamine problem (aka allergies ~ caused by who knows what or how many things). I get this too, but it didn't really start badly until I was thirty five (fifteen years ago). I nearly went into anaphylactic shock one day. After an adrenalin shot, and taking a strong antihistamine for a day or so, it finally went away after a week of it from head to toe.
You don't want to mess around with that kind of thing. It can get much worse over time, and if it is allergies, can develop into much worse things, some of which can kill you.
I still itch a lot, but I don't break out in full blown hives very often anymore. When I had that bout in '95 I had hives over every inch of my body. It was so bad I was vomiting.
Do you actually get hives? If it's bad enough you're cutting open mosquito bites, that's serious.
Get that looked at man. Seriously.
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I'm not likely to be around much longer. As before when I first signed up here years ago, I'm finding that after a long hiatus, and after only a few days back on here, I'm spending way too much time here again already. So I'm requesting my account be locked, banned or whatever. It's just time. Until then, well, I dunno...