lighting in my video making my track move

So I'm trying to make my tracker track the hand of the person I filmed for this scene where I want the hand to have fire in it. The thing is, the scene is kind of dark and there's a light I have off to the side where it's in a paparazzi mode and it flashes every so often. the hand I'm trying to track is backhand towards the camera and you can see a little of the palm so I tried to track that and it went pretty good till the lights flashed and it's like the tracker took the direction of where the light was flashing on the hand. The only part that doesn't suddenly get lit up from the flash of light is the back of the hand, and when I tried to track the back of the hand, it's just really sloppy. Could someone possibly help me out with this problem? I've already spent too much on this edit.

The trackers work on areas of contrast and expect some degree of consistency, which the "flashes" of light are probably throwing off.

If you cannot find a trackable point on the hand you will need to take steps to correct the contrast (you could branch off the footage with a set of nodes that filter the image in some way to create something that might look bad to a human but provides good contrast for the tracker, then simply not use that branch to produce your final output - just track from it), or use different points to track different sections of the footage (start tracking and watch for the tracker to start wandering, then find a point just before it goes bad and restart the track from there with it tracking from a different point).

If there are parts of the footage where the contrast is so bad that it simply won't track, you may have no choice but to manually tweak the path for that part of the footage.

Do a manual fix for those flash bits as Frank suggested, not everything can be autotracked, better spend the futzing time in fixing those erratic ranges. If flashes are short and hand movement is smooth, just delete the intermediate parts of track path.