comet really acting weird

my comet has started flipping out today. He will act fine, swim around
normally and then he starts bobbing and weaving.......meaning he will stay
still, but while doing this will weave from side to side......going from
being normal, to a laying down position....think of it this way hold your
hand flat......representing him normal and then turn tiurn it like you were
going to shake someones hand....and then do it fast......thats what he does,
and then he totally flips out.........darting all over the tank, hitting
rocks the side and really thumping the hood of the tank hard.........and
then returning to being totally normal.......eating normal etc.

i have seen fish rub themselves on the bottom of the tank and dart around
due to ick, or water conditions, but nothing like this.......theres no red
streaking on the fish, theres nothing noticeable at all on the fish, no
other fish are acting this way, and my water params are just about
perfect........

does anyone have any idea what is going on here???