Not me, but my girlfriend - for the last month or so, whenever she gets nervous or worked up (be it from arguing with me or her daughter, dealing with her boss, or just talking about something she is passionate about), she has started shivering uncontrollably. This is not something that is usual for her, and has only been happening for the past month. She’s somewhat concerned, but does not have health insurance and I can’t seem to convince her to go to a doc yet because she doesn’t think it’s anything too bad.
I’m not a doctor, but it could be a couple of things in my mind: adrenaline and anxiety. I know about the latter, as I’ve struggled with it for the better part of 10 years. When I was in junior high band, I used to get so nervous during our chair tests (where we had to play a piece of music out loud and were seated according to our performance) that I would begin to shake uncontrollably. My folks finally took me to the doctor. He diagnosed me with anxiety and gave me a prescription for Xanax, with strict instructions to take it only before the triggering event. It worked pretty well for me.
Again, IANA doctor. Maybe Pedant or one of our other medical dopers will be along in a bit.
It’s an anxiety reaction. I’ve had panic attacks for years (I take ativan to quash them), and I get the shiver attacks often with/during an anxiety attack or completely separate from an actual anxiety attack. Anxiety-provoking situations are always the cause, though.
I had a “shiver attack” just last night after getting in a big, emotional argument with a friend over the phone. It got so bad that my teeth were chattering like I was out in a blizzard and had to hang up for a while.