Hi Blackmoth,
Sounds like your having a hard time, but dont worry the anxiety does go away, that is if you stop taking drugs.
When I was 18 I was a heavy user of trips, never really knew how much lsd was in them, but after about 1 year of abuse I started having tachycardia, and heart pulpitations. It was the worst feeling I have ever had. It lasted 6 months and I had to take beta-blockers (slow down your heart) which really helped. I also ended up in rehab for 1 month which also helped alot, I didnt think that I needed it, but looking back it did help.
The purple hands and feet are a result of poor circulation, I have it still do this day, but no where near as bad. My thought is that the stimulants that I abused have stuffed up my nervous system, and when I panic or feel anxiety it cause a traumatic response in my body, restricting the vains it my outer limbs.
The best thing that I did was talk to someone about my problem. Not one of my mates, they all took drugs and didnt have a problem (at that point in time, but they all did later) someone that you trust, even if you know that the news will disappoint them. You need help from others! And people will help you.
This is only a tiny part of the full story I went through, and I think I'm just baffling on now. So I leave you with this Blackmoth.... Talk to someone you trust, stop taking drugs.. for a awhile at least, oh! and once you feel your anxiety fading a little exercise is always good! (Dont worry, you wont have a heart attack, just take it easy)
Oh, yeah, one more thing, I was also prescribed anti-depressants, I dont know if it really helped me, they made me numb emotionally, but they may help. And far be it from me to say not to take them if a profession tells you to go down that option.
I really hope this helps, if not please reply with an abusive post! Things do get better mate..