I seem to get them often too. I have no idea if it was from the chemo in the past or not. I have read they can caused from being overtired, or not enough oxygen. Thorazine is one of the drugs used to get rid of them but it will make you sleepy.
Someone in my small group bible study said she had heard if you say out loud " What color is a white horse." It would get rid of them, well I laughed it off, but I did try it and about 3 out of 4 times it worked. Goofy I know but thought I would pass it on.
Cindy