Shine the flashlight on gill area and see if when he breathes you can't see specks of velvet on his gills. Also you may be able to see some specks on his fin membrane.
I had velvet go through my entire fish room (learned not to share equipment) and I had to euthanise a whole breeding group of fish as well as losing two of my homebred adults. Velvet is extremely nasty and can hide itself well on fish that have a lot of natural iridescence.
If he has been hiding a lot, gone off his food, is breathing especially fast and scratching frequently, it may be velvet. My fish had big ulcers around their heads because they had scratched themselves so hard. They looked very pitiful and near death for weeks and it took me a month, maybe more to finally eradicate velvet from my tanks.
If it is velvet, I bumped the temperature right up, used a copper based medication and covered my tanks so no light came through. This seemed to kill the velvet off I haven't seen it come back at all.
Just be aware that if it is velvet and it seems to go away that like ich it has a longish lifecycle and can still be there waiting to infect your fish if you stop medicating earlier on.
I found aquarium salt and just bumping the temperature was not enough to kill it off and I lost two fish while I fumbled about.
(Velvet is very small to look at. Also if you look down the length of your betta's body it will look like a sort of greyish or goldish dust. Almost like your fish has been rolled in a fine sand or powder http://www.petfish.net/articles/pix/arts3/velvet.jpg