Your UVB is not strong enough I would replace that immediately. Dragons need a Reptisun 10.0 T5 bulb. The 5.0 is way too weak for Dragon's needs. The Veggies need some Improvement. Onins are toxic. They contain an ingredient called thiosulphate. This can cause Hemolytic anemia. You can feed dandelion greens, butternut squash, escarole curly endives. This is a veggies nutrition sheet: http://www.beautifuldragons.com/Nutrition.html
Now as far as prey, No meal worms or super worms. They are not digestible due to the high amount of chitin, the can also cause Liver problems due to the high amount of fat.
Silk worms, dubia roaches, crickets horn worms and Phoenix worms are all acceptable.
Calcium should be 5 days a week and 2 days on the Vitamins.
Now for some First ail. Please give him a soak in a 50/50 Pedialyte soak for 20 mins. Make the water warm. When in the soak gently massage the abdomen from snout to vent. He may produce a stool. Tis soak is to warm up the body as well as hydrating him.
For emergency feeding use chicken baby food one part to green bean baby food one part and add some calcium and drop on snout to get him to lick it. He should weiilingly accept it.
He should perk up with the changes. If he does not, a Herp Vet will be needed. He may have a parasite issue, an organ issue or may be some type of an infection going on. If you need a Herp Vet please supply a State and I can locate some for you.