Muscle tremors. That's a sign of improper calcium metabolism. Some people think it indicates metabolic bone disease, but that isn't so all the time. He NEEDS UV, he should likely also receive a multi-vitamin injection, specifically with D3 and selenium if possible, some calcium supplement, and possibly also calcitonin, depending on how serious the condition seems. IE - as several people have said, he should seriously be taken to a vet.
I've cleared up tremors with UV and vitamin injections. Contrary to what some people may claim, young tegus need UV, and older tegus should still get it. Claiming that with proper supplementation you won't need UV is like saying you can live off of Kraft dinner and ramen noodles as long as you take your Centrum.
As for what will provide enough UV, I find if you get just simple full spectrum fluorescent grow lights from the hardware store, they do fine for tegus. The D3-Calcium metabolism-UV pathways are poorly understood, and there does not seem to be any evidence that stronger UV is better.
But please, get the poor guy to a vet, get some calcium and vitamins into him, and get him some UV.