I think the first thing you should do is separate the more aggressive eaters from those that are not feeding as well. The next thing I would do is get as many fresh poop samples as you can and bring them to a qualified reptile vet right away to test for parasites. It is likely that one or more may have had parasites, and it has spread through the lot of them. This can be treated with medication. I don't want to scare you, and I think that you should take care of this promptly. The more aggressive ones may be scaring the less aggressive causing them to go downhill quickly. I would separate as many as you possibly can. I had a non-eater also who turned out to have coccidia. I used a mixture of collard greens, mustard greens, turnip greens, yellow squash, juvenile repcal pellets, and yes, even crickets (yuck) and blended them into a liquid. I would draw it up in a needleless syringe, but prior to that, I would dust with calcium and mix that in. Soon she was eating on her own, and now she is a big girl, 8 months old, and almost 20" long and almost 400 grams. The most important thing you must do is get a fecal to the vet right away (I mean like tomorrow), as fresh as possible, and separate them ASAP.