I'm concerned because you are saying your chameleon's eyes are slightly sunken and that he still isn't opening his eyes. If a solution isn't found quickly, then I recommend going to a vet.
Sorry if I have asked these questions before...but I can't remember everyone's details. I answer too many posts and I can't keep them all straight...or spend time looking up previous posts.
Correct temperatures are important for digestion and thus nutrient absorption. Calcium, phosphorous, D3 (thus UVB) and vitamin A are all important in bone health and need to be in balance. Preformed vitamin A can build up in the chameleon's system, beta carotene sources can't. Vitamin D3 from supplements can build up in the system...but D3 produced from sunlight/UVB can't.
You said..."u're right about the Zoo Med basking light not emiting full spectrum light, so I rushed down to get myself one yesterday. I'm now using the Arcadia Extra High Output 7% UVB D3 Compact Reptile Lanp, is that good enough?"...I don't think I have ever used that bulb...is it the one pictured here under "Zoo Med Compact Reptisun" in the following site? They don't list a 7% one here though. The light shouldn't pass through glass or plastic or the UVB won't be any good, BTW.
http://www.robharvey.com/reptiles/lighting.htm
I usually use Repti-Sun 5.0's florescent tubes. I try to remain consistant in which bulbs I use so I don't have to adjust my supplementation. I use a regular incandescent light in a metal hood for a basking light. Use the wattage that gives you the correct basking temperature.
Direct sunlight would help too...is it too cold to take him outside?
What are the temperatures in the cage under the basking area and in other areas of the cage away from the basking light? (I always put my basking light on one end of the cage so that it gives a warm side and a cool side.) You don't want to bake him! Is he sitting under the basking light or in the cooler area of the cage?
You said...As for the feeders, I give the crix T-rex high calcium crix formula, I also throw Zoo Life Vitamin Powder into the feeder bowl, but my cham has never eaten from the bowl for the 1 month he's been with me. So the ones he eats are the free roaming ones with no powder on them"...I free-roam all my insects and I dust them before I put them in the cage. I know the dust will fall off if they are there too long...but they will at least get some with dust on.
I dust with a phosphorous-free calcium powder at most feedings. Insects have a poor ratio of calcium to phos. so dusting with calcium helps to balance it out.
I use a vitamin powder twice a month and its one that has a beta carotene source of vitamin A (see comments above about vitamin A).
Because my chameleons don't usually get direct sunlight, I dust lightly with a calcium/D3 powder twice a month. I also use a wide variety of greens and veggies, etc. to feed to my crickets and try to give other insects I have a nutritious diet too. I'm not a fan of commercial diets....but again, its just my opinion.
What source of vitamin A is in the gutload and vitamins you use? Is there any vitamin D3 in either?
You said..."His eyes were slightly sunken this afternoon, and his eyes still closed. So I mixed a little of the vitamin water into water n forced fed him. Is that alright?"...I only use vitamins twice a month as I said above. You said he's eating and drinking...so if the insects are well fed and dusted properly then you don't need to do this. Since he hasn't been getting UVB...has he been getting D3 from the gutload or vitamins?
You said..."My only consolation so far is that his grip is much firmer than yesterday's. Perhaps the UVB lighting is doing him some good, I really hope it isn't too late"...I don't know how fast the light would work. I hope its not too late too.
Hope some of this helps...and that I haven't overwhelmed you!