yeah your temps in your tank could be playing a role, also allot of beardies will go off feed aound winter time. usually when this happends they are going into brumation (aka hibernating) juveniles usually don't brumate but you never know. I am havng a problem at the moment with my 6 mo. old he will only eat his greens at the moment. keep offering your beardie fresh greens and squash. I guarantee if you shred up some squash and toss it in the microwave for about 10 seconds he will eat it. try a warm soak in water to stimulate a bowel movement. Oh stay away from just regular lettuce it has no nutritional value for your beardie at all. It's just full of water, use mustard grens , collard greens, escarole, strawberry tops, cilantro, alfalfa.
here is a good feeding chart
http://www.beautifuldragons.503xtrem...Nutrition.html