Phil as difficult as it is I'd try not to feel about at veins, etc. because you'll only wind yourself up more and more. Try to accept that you are suffering from an anxiety state and that it will dampen down with time if you try not to focus on every strange ache or pain. When we are anxious we hang on to every thought and feeling. Try and distract yourself and you'll be more relaxed and these things won't worry you so much. I know it's so difficult but you can get through this if you ACCEPT and let time pass.