I suppose it's possible that you do have some illness that no doctor has been able to diagnose. I'm also a pretty calm guy and don't often get "stressed" in th

I suppose it's possible that you do have some illness that no doctor has been able to diagnose. I'm also a pretty calm guy and don't often get "stressed" in the typical sense, but also had similar symptoms to you which also couldn't be diagnosed or observed by doctors. Impression of me then: "I've stayed up late for months now, drinking coffee alone, working, and trying to figure out what could possibly be causing these anxiety-like problems. I've checked the symptoms for cancer, AIDS, Lyme disease, and general death repeatedly and nothing quite fits. What...could...be....causing 'attacks' of 'anxiety'....hmmm sips coffee" :) If you're sleeping well, a normal weight, not intaking alcohol and caffeine, it'll at least rule a few things out.