Mmm what do his urates look like? This looks like dehydration. Infections cause swelling not sinking. 15 seconds every hour can be okay if you a lot of live plants. But I mist every 3 for 2 minutes in a bioactive enclosure, so it retains a lot of moisture and water. If the urates are orangish in color you can either turn up the spraying a little bit more, he may be drinking and not getting enough, or try a 30-45 minute shower (look up how to shower a chameleon before doing this) the shower is usually a last resort though.
I’m not a vet, nor a particularly well informed Chammer; however, the last Cham I rescued came to me with her eye swollen shut. The previous owner said she was blind in one eye. There was discharge and general crud around the eye. I took her to the vet, who flushed the eye out, and gave me some antibiotic eye drops to give twice/day for 10 days. The whole thing cost me like $100 Canadian (so probably like 4$ us), and my girl now has two fully functioning eyes, and an attitude to stop traffic. Point is, for $100, the problem was fixed with no harm done.
Your Chameleon - Veiled cham. About a year and a half old male.
Handling - Almost never.
Feeding - He gets fed calcium dusted crickets, dubai beetles, and worms. I switch these every day and he gets a fairly large amount.
Supplements - I dust my feeders with calcium without D3 every other day.
Should be everyday calcium no D3, once every two weeks multivitamin with vitamin A Retinol, and once every 2 weeks calcium with D3.
Watering - I often see him drinking off of his leaves. I have a misting system that happens every hour for 15 seconds.
As said above your sessions should be longer. No less than a minute but don't really need to go over 2 minutes for a veiled. I do 2 minutes every 4hrs for my Veiled.
Fecal Description - His fecal matter is very normal. Never been tested for parasites.
History - When we received him he had issues with weak bones and was very calcium deficient.
Was he diagnosed by a vet with having MBD? And if he's calcium deficient why aren't you giving him calcium everyday?!
Cage Type - screen cage
Lighting - 12 hour UVB light, all the time heat lamp.
UVB bulb linear or compact? Should be a T5HO linear UVB bulb. You should immediately stop the heat lamp at night. Chameleons need complete darkness to sleep and can take night drops in the low 50s.
Temperature - hot spot is 90-80 everywhere else is 80-65.
Humidity - Always at 60-50%
Humidity should not be constant but fluctuate. 40% during the day and up to 70% at night for Veileds.
Plants - Large umbrella plant.
Placement - Corner of very open room. No vents.
Location - Mid west
Current Problem - his eye.
My recommendation is to get him to a vet asap. And correct your husbandry issues. No more night light! I'd suggest picking up a multivitamin with vitamin A Retinol such as Repashy Calcium Plus LoD. Vitamin A is super important for chameleons eyes.