Hi there glanzer
i've also had symtoms like you, muscle spasms, lack of appetite, feeling shaky, week-kneed, finding it hard to get to sleep and when I do I wake during the night, and generally just that run-down kind of feeling. I also for no apparent reason seem to get cold/flu like symptoms and like yourself I dont end off with the cold/flu.
I had my worst panic attack on 10 jan 2006 and honestly thought it was a heart attack to the point where I called out loud 'oh please no', at that time I was off work with possibly some kind of virus tho my dr isn't sure and my mum thought maybe I was worried about being off work!
I've not had a major panic attack like that again tho I think i've had a few smaller ones as though maybe it was going to happen but I think i've managed to stay calm enough to control it, all that happened was I got the hot flush n rush up feeling and before anything else happened I took a few deep breath and tried to relax as much as I could but its still scarey.
I forgot to speak to my dr about these attacks last time I saw her but feel a bit guilty having to make yet another appointment as I never seem to have been away from the place recently.
I do have an under-active thyroid but thats kept well checked and the levels are fine and recently had a full blood test done and everything came back negative - so why do I still feel anxious?