Sounds like a lot is going wrong here. First thing, he needs his OWN tank. Dragons are solitary creatures and living with another animal will stress them out. Second, you need a Reptisun 10.0 tube
UVB light, or a MVB such as MegaRay as the
UVB light. It needs to be this specific kind, or you will run into many problems such as metabolic bone disease and stunted growth, or lack of appetite. The heat light needs to get the basking spot to about 100 degrees or the dragon can't digest his food. You will need a digital thermometer with a probe - not the stick on or dial thermometers. They are not accurate. Also if you have him on any type of loose substrate like sand or calcisand, I recommend getting rid of that right away and using paper towels, shelf liner, or tiles.
Good luck. If you aren't able to get the dragon food that he needs, at least get him some greens for now until you can get bugs. Collard greens, turnip greens, or dandelion greens are a good choice, not lettuce.