Hello:
You should have something to read the humidity in the tank, you can pull the snake out of the water and check in the water bowl for little black specs, if you see them, than the snake has mites. Your best bet is to google PAM. It can be ordered offline and is the most recommended around the site.
The reason I say you need to buy something to measure humidity, is because your snake will ned a constant 60% humidity. When the shed cycle starts, you should bump this up.. Few mists a day should do the trick.
Do you have the snake in an aquarium or a tub? And if you believe the snake may have mites, take out the bedding and put them on paper towel, this makes it easier to tell if the snake has mites.
Your ambient temps seem a bit high as well. I believe 82-84 is recommended.
Cheers,
Mike