Beardie might have mbd. Help.

Being that this is an acutely ill bearded dragon, I mostly defer to Tracie on this matter. That being said, in addition to needing a better UVB source (NOT at night), he also looks severely malnourished. At his age he should be getting two feedings of live insects daily. He should be allowed to eat as much as he can during each feeding - not limited to 6-7 crickets every other day. If he's refusing to eat, however, you'll probably have to drop feed on his nose or - worst case scenario - force feed him. If you struggle to do that with feeders then you can get something called "critical care" that you can feed through a syringe to their mouth.

That said, getting him an appropriate UVB is the priority right now. Set up the reptisun 10 (make sure it is the t5, rather than the t8), and make sure he can get about 6-8" to it with no barrier inbetween the beardie and the UVB. As for when to have the lights on... Only have lights on him during the day. Bearded dragons are very sensitive to light and do not sleep well in any thing other than total darkness. Leave his UVB and basking heat light on together for about 14 hours (maybe longer until he gets better, but again, I defer to Tracie there), and then total darkness at night so he can sleep soundly. Do not use anything that is sold as a "night light" when he is trying to sleep. Bearded dragons can still see the different colors of light.