So i haven't had a gecko with mites but when i tried to have my first snake, it came in with mites. They were small white specks that moved around. They stayed where the snake was most moist meaning eyes and face. The red dots could be irritation. I don't see it on the picture you supplied but if there are a whole bunch of crickets in the enclosure they could be going after him. There should never be left over incests that could pick at or distress the gecko.