It sounds like you are very concerned about him, that is nice to see such caring and concerned new owners. You have come to the right place
I am going to try my best to tell you what you're doing well and what needs to be changed, but I'm half asleep, so I hope someone else chimes in and gives info too.
You need to shut off all lights at night. He needs no heat or light at night, and that is how it should be for their health. It is fine if it gets down in the 60's at night. During the day, it needs to be about 68-75 degrees, no more than 75, in the majority of his cage. This species is from an area of the world where it is cooler. We tend to think that all reptiles like it hot, but it is not true with some chameleons. That means that you probably don't need the basking light. And the basking light should never be in the middle of the cage, it should be off to one side so it covers only a small area of the cage. And 150 watts is way too high. You should get a temperature gun and measure the area under the basking bulb, because it shouldn't be more than about 83 degrees for this species at the hottest point. It you have a 150 watt bulb in the middle of the cage, I guarantee that it is getting way too hot for him. Get a smaller wattage bulb, like 40 watts, and try to elevate it off the screen somehow because they cling to the screen right under the bulb and can be fatally burned. This will give him the option to get warmer if he feels like it, and like I said, make sure the hottest part of the cage does not get above 83, plus or minus a couple degrees, and that should only by a very small basking area taking up very little of the cage.
As far a supplementing, make sure the Repcal you are using doesn't have vitamin D3 in it or any other vitamins, that it is just calcium and give a tiny amount of it with the worms at every other feeding, some people say every feeding. Give vitamin D3 once every 2 weeks or so, and give a multivitamin about once every 2 weeks or so. As far as him not eating crickets, he may not be used to them, or he may be stressed from the heat. You should really get a temperature gun, you can get them online or go to a hardware store and see if they have one. I bought one for $13 and compared it to the expensive ones and it is very accurate. That way you can measure the temperature of different areas of the cage.
As far as hydration, it sounds like you are doing a great job. I would get one of those pump sprayers that you get in the gardening section of the hardware store, that way you can spray him for several minutes for the first spraying of each day. After the lights come on, I wait about an hour and spray them for 5 minutes or longer, then the sprayings later that day are less.
It sounds like he isn't defecating, I would feed him wax worms. They are the white, fatty worms that are sold next to the meal worms. They are very soft bodied, and if he has and constipation or impaction issues, they should help. Once you have the beginning things figured out, then you can alter his diet with silkworms, hornworms, and roaches. But I would definitely switch to wax worms for a few days to get things moving through his intestines.
So most importantly, decrease the heat, get some waxworms/grubworms, and make sure you are only giving him calcium at each or every other feeding (a small amount) and vitamin D3 and multivitamins once every few weeks, but I would give multivitamins and D3 to him soon because he is probably low given he is most likely wild-caught.
I always tell people that it is important to take your chameleon to the vet, this advice on here is not medical advice and should not take the place of the medical advice a vet will give you and treatments the vet may give. He could be constipated from having parasites, so the vet will check a fecal and give dewormer. Also, the UV light, is that a long tube light or coil? The long tube fluorescent lights are best because they disperse the UVB light more evenly so he has a better chance of absorbing it. Also, the 2.0 might be too low since it is on top of the screen, you may want to think of a way of mounting it under the screen since screens filter out UV light, or go up to a 5.0 UVB
I know I missed some things and may have accidentally said things incorrectly, but I guarantee someone will correct me if I did and tell you the things I forgot. If you have more questions, do not hesitate to ask, and keep us updated. Also, a picture of your chameleon close up and of his enclosure would really help. I would also go through the gallery images on this website to look at other people's set-ups.
Thanks for asking, everyone loves to help
