Sounds like a bad rollercoaster ride. But then again, it's only blitz. Those 5 minute games are good to test some openings or, if you get so far, your newly studied endgame.So i wouldn't worry to much being a stock market imitator with your blitz rating. When your standard rating becomes a copy of the stock market i would be worried more since that would mean something is smelly in improvement land.
I agree with chesstiger. Testing openings, seeing better simple tactics, etc. - this is what you get with blitz. There are many more things that affect your OTB play, the only real measure of your strength. Maybe you play being tired, or too much - check it. Try to change the time of playing, number of games, openings, etc.I had real slumps on FICS, then I always recovered to my average rating.
Rocky,My rating has been known to drop 300 points in a single sitting. I usually get it back up with sensible playing for a week or two.