Just updating this in case anyone else has the same mystery. I think this is a sinus issue.

I have been having some low-grade tooth pain and worried that I had bad breath. I went to the dentist today because the pain in my wisdom tooth area was pretty constant.

My teeth are fine. I told my dentist about my recent vision thing. She suggested that this is a sinus issue - the sinus membrane overlaps with the wisdom tooth area. When I got home, I googled and found that flashing lights are also connected to sinus issues.

So the light flashing + tooth pain + bad breath seems to indicate that this is a sinus issue. I don't really have a stuffed up nose or any of the other symptoms. Now that I think about it, the light flashing problem started right around Thanksgiving, which is when I had a strange sort of cold.