Lethargic: of, pertaining to, or affected with lethargy; drowsy; sluggish.
If he is shedding your chameleon should not be lethargic. Shedding is uncomfortable but they should be moving a lot, trying to rub the skin off on branches or stretching themselves out.
It might be useful to fill out the Help Form so we can try to figure out what's going on. Is the basking temp warm enough? Have you looked in his mouth for signs of excessive mucus/saliva/bubbles? Perhaps he is brewing an infection of some sort. Photos would help as well, if possible.