Wow-this is very sad. THIS is typical Petstore set-up and care. Just so you know-this is exactly what happened to me the first time out but mine only made it 4 days.

It has all been said already, but I will try to make it as simple as possible.
a. Please don't put the cham in the glass tank in the sun-you will cook him, but I am sure if you could put him on a plant in the sun and sit there and watch him for a bit that would not be a bad thing.
b. Maybe just turn off the light for now if you have no idea how hot-if you put a 60W bulb on a glass aquarium it get real hot real fast. OR-get a digital thermometer with a probe on the end and check the temps on both sides and in the middle of the cage. Put the probe in the spot you want it then wait 3 minutes and read the temperature. I really would not want it higher than 90 on one side and it shoud almost be room temp on the other side so he can get out of the heat.
1. Get to the Vet Asap-he can get you started with a Calcium shot.
2. Set him up with the right supplies-here is a list of what you need...
Shopping cart
Zoo Med 18" 5.0 UVB bulb
$13.99 each $13.99
38 gallon basic Reptarium (or screen cage-your choice)
$26.99 each $26.99
Regular Clip lamp
$5.99 each $5.99
20" fluorescent hood fixture (or Walmart undercabinet fixture)
$26.99 each $26.99
Exo Terra Jungle Vine Medium
$7.99 each $7.99
RepCal ultra fine calcium with D3
$4.99 each $4.99
Rep Cal Calcium WITHOUT D3
$4.99 each $4.99
RepCal Herptivite supplement
$8.99 each $8.99
You can save some money by getting a Walmart $8.00 fixture to hold the flourescent bulb and right now LLL has a great screen cage that is 18X18X36 on sale for 57.99 that I like a little more than the Reptarium. You can put a nice size ficus or schefflera in there. A regular lightbulb can be used for basking and it sounds like you have the clip lamp. If you look at my website in my signature it shows pictures of the things in the shopping list for reference.
We all know that this can get expensive. Another option would be to give him to someone more experienced to get him better. All of his problems really are related to lack of supplementing with the right things, incorrect lighting, and incorrect temps. Good luck and we will be happy to help you help him get better. They can go on to live a good life when the problems are fixed, but at the point you don't have much time to get them fixed.