Hm, Is it possible that your little one is a female? We were convinced our sweet girl was really sick for a while, and then we came home to like 16 eggs in her enclosure, and she was skinny, but her personality was back. Has he/she been eating more than normal? Or gained any weight? I really hope that she gets better, but as long as she is eating and pooping normally, then I wouldn't worry a ton about it, they have all of their own ways of acting about certain things.
Do you take her outside? Or ever let her out of her enclosure?
Both of our girls will get a little sad sometimes, but usually a nice warm
bath (I know yours doesn't like them, but ours seem to love them) or taking them outside in the summer usually helps perk up their moral. They all like different things, but you can always start trying stuff to perk your little guy up!
I would like to add that I am in no way an expert, I am still learning as I go with our 2 girls, so I am just trying to think of as many things as possible to help you with your Beardie, I know how much these guys grow on ya, and it's terrible to see some one worried about them!