So your keeping 11 big 1 month old babies in a 20 gallon glong tank? If thats true I suggest you get another couple 20 gallon long tanks to seperate them.
2nd off, Your going to want to order crickets in bulk pretty darn soon. Your going to be spending about $30 at least from a pet shop for all these babies if you feed them correctly. A 1 month old - a 6 month old can easily consume 20 -100+ crickets a DAY! At 4 month old Mine easily wooofs down 110 crickets plus a relatively large salad and 8 rep cal pellets a DAy. You you feed salad in the moring IF the will eat it and offer live insects 2-3 times a day. Make sure each one gets as many crickets as it will eat in a 10 minute period if you want opyimal healthiness, growth, and happiness. I've seeen dragons get to 20" within 9 months on this schedule, and the longest lived dragons that got to 11-13 years ate lots o crickets at an early age.
Get yourself a 20 gallon long or a 15 gallon aquarium, which should house.... oh I'd say close to 2,500 crickets. Order 2,000 or 3,000 crickets from one of the following places for them to ship to you. Trust me, rather than paying 10 cents a cricket yull be paying closer to 1 cent a cricket. Take a look at these sites and makee sure the crickets you feed are no larger then the space bettween the dragon eyes
Ok, now for the sick little ones. Quartine ALL of them! Get each on their own 10 gaooln aquariums or tubberware containers that come to close that size. All they need is a basking rock, something to get within 8 inches of the UV light, and food dish inside the cage. Outside the cage a heat lamp and UV tube/light of course. Keep the substrate/bottom only paper towel and clean poo up the moment you see it. no water dish is needed (bad stories about them I will exaplin later).
Before you do any of this I recommend taking the dragon(s) to the vet ASAP. Could be a respiratory infection, or I'm think cocidea.
After the vet and cage see if anything gets better, could be the cagemates. But if its not keep offering chicken babyfood of some kind. The vet may give you instuctions on how to force feed if no progress is made.
This is a difficult situation, I'll try my best to help you out.
Hoep this isnt tooo confusing, had a lot in my head. I believe i said everything needed....