O...M...G... as far as I understand it, hot and cold contrast therapy is STONE AGE thinking as far as CRPS goes. You need them to stop that straight away. It used to be considered a good therapy to get your skin used to feeling temperatures more normally - but the extremes of it are bad bad bad long-term, and it is not recommended now (it can even cause spread). The clue is the bad pain with the cold - with CRPS, anything that causes a bad spike in pain must be avoided, from intensive physio to super-cold water...

That vein thing sounds weird, I can understand you being worried about it, especially if the hair around it has gone, as with the other affected areas. All you can do is ask your doc and physio what they think, and take it from there.

Good luck with your appointment, I hope it goes well and they can come up with some new treatments for you!

Bram.