My son used to have itchy skin that would turn red, but mostly on his back and mostly when he had hot spells. Since he doesn't have the hot spells any more, he also doesn't have the red itchy skin.
He used to jump in a cool shower and it would make it stop. Also, if a shower was not available or too busy for it, benedryl lotion helped.
The fact that it's your face, arms and chest makes me think of flushing ... is it flushing? Have you seen the flushing pictures on my profile? (Click on where it says my username heiferly to go to my profile page and then browse through my photos to find them.) I have some newer ones that may be even better pics of my flushing episodes that I'll try to put up there today if I can. On the other hand, I don't know that flushing usually itches ... have you had MCAD/masto ruled out? If you know that you can safely take the OTC meds benadryl as well as either zantac or tagamet, you might try that just to see if it helps. This would be combining an h1 antihistamine (benadryl) with an h2 antihistamine (either of the two "stomach" meds I listed), and is sort of a one-two punch for certain types of allergic responses. At the least, it can be tried with easily available OTC meds and little hassle and you haven't lost much $$ if it doesn't end up being the solution.
My itchiness comes in little patches rather than correlating with my flushing rashes; are yours covering the exact same areas?
Also, one note with benadryl: some people with dysauto have trouble with drugs in the class that benadryl is in ("classic" h1 antihistamines, including benadryl, promethazine, and many others ... keep an eye out for flaring up of dysauto episodes such as bp spikes or crashes, dramatic changes in HR, etc. when taking these drugs to know if you're unable to tolerate them). There are other h1 antihistamines ("second generation" h1s) that are less likely to cause these problems in susceptible dysautonomians. Talk to your doctor or pharmacist before taking them even though they're OTC if you don't know if these drugs are safe for you and/or have never taken them before.
Well, I'll get some more flushing pics up ASAP. Sorry you're so miserable with the itching. :-(
-H.