I know in humans there are temporal pouches...don t know where exactly they are in panther chameleons.
(Jacksons have temporal glands in the corners of their mouths...that's all I know about location wise.)
Because there is an area on both sides of the mouth it's not like it was an insect bite...it's either something physical that is there or he bit down evenlynon something I would think.
Can't tell you about the vitamin A injection. Does he get any prEformed vitamin A now in his supplements?
Sorry I can't be of more help.