White flashes happen before, during and after a vitreous detachment. This is where the vitreous inside your eyeballs shrinks with age and at some point it detaches from the back of the eyeball. Not saying that's what you have, but I've had flashes and that's what they have been. Not TMS.
I would like to second what Jeff said. He is absolutely right. I have had the flashes due to the vitreous detachment. However it continued on for several months. I had seen my ophthalmologist who checked my retina and said it was okay. On a follow-up visit where I was still having the flashes he referred me to a retina specialist. It took the specialist only a few minutes to detect a tear in my retina. It was so old at that time it was healing itself, but that leaves me with a loss of vision in that area. Fortunately it is so peripheral I actually don't see it. In any case I walked from the exam room to a surgical room where he performed laser surgery on my tear. Personally I would HIGHLY recommend a visit to your retinal specialist to be checked. You may not have a tear, but as long as you still see flashes it could happen. You only have one chance at saving your sight. I only wish I had gone earlier. Best of luck to you.