Slytherin88... I used to wear tutrleneck shirts all the time for the rash but if not I would take propanolol it helped a lot. I have both blushing and the rash/blotches... when I blush it's not really a "blush" but my entire face looking like it's about to freakin explode because it is so red.
I was subscribed prop****ol and didn't find it helped, the dermatologist was a foreign lady and didn't want to listen or look at the photos I had where the rash had ruined special occasions. Makeup doesn't work, I'm fair skinned so tanning and sun makes it worse. The main thing I've done is tried to put myself in the situation that made me rash up and then I'd get used to it and it has subsided. I can't think of an occurrence in the last 6 months so I am feeling lucky.. I don't mind blushing so much, when like embarrassed, but yes as you say, this isn't a blush, it is a full on rash up my neck and face.
Fun fact, there was an episode on Embarrassing Bodies (I don't know if you get there where you are) and there was a lady with it. She did CBT, and thats what got me into it, and what bought to light the SP/A.
Have you always had the rash, or has it just been in adulthood? I have only had it since I had glandular fever when I was 17, and had a reaction to an antibiotic, and since then that rash has come back when stressed/tipsy/angry/upset.