I can get that way when my salt is low (got it more as a kid, when I actually went outside and broke a sweat <img src="i/expressions/face-icon-small-wink.gif" border="0"> ). I also get that way when my bloodsugar is starting to get low (then I get sweats and shaking, weakness). And finally-lol-sometimes my Xopenex does that to me, if my lungs are really clear- I guess more of the med gets into my system then? I dunno...
I hope you can get to the bottom of it soon!