help

I can't sleep.
Sunday I started getting a little shaky. Not too bad, just a little shaky and nervous. The next day I woke up a bit early, spent the morning shaky and anxious, felt a little better by afternoon. Each day has gotten a bit worse. Yesterday I spent the day going between anxiety attack and sobbing fit. Today I woke up at 1:30AM - and I can't get back to sleep.
Many of you know I've been on antidepressants for 5 years. I was very lucky - the first one I tried worked for me. I've felt normal - with only 2 setbacks, for 5 years. I know how lucky I've been, I've never taken it for granted. So why, all of a sudden, does it feel like I'm not on anything at all. Why do I feel like I'm going slowly and uncomfortably crazy?
I don't mean to make it sound like I'm the only person to ever suffer this crap, but if you have anxiety issues, then you understand - it makes you very self-focused. All I think about is the fact that I can't calm down, my stomach feels a constant dropping and nausea (and hunger, since I can't seem to eat), and I'm absolutely miserable.
I have made a doctor's appointment for later today. I'm hoping he can do something for this. Wish me luck, please.