The biggest danger for this little one is dehydration, so I'll give you a first aid measure to take. Buy some unflavored Pedialyte (yes, the kind for human infants). Prepare a shallow
bath consisting of 1/2 water and 1/2 Pedilayte. Soak your beardie for about 20 to 30 minutes at least twice a day. Reptiles can absorb the electrolytes and fluids through their vents (where droppings pass out), so make the water deep enough to cover the vent. Since he is weak, you may have to hold his head up during the soak. Be sure to supervise closely. This will not take the place of a visit to the herp vet, but may help the beardie stay stronger until you can get there.
It would also be a good idea to increase the temperatures. For one this young, the basking area should be 110-125 degrees F (43.5* to 51.5*C) and the cool side: 85-90 (29.5* to 32*C).
Once the dragon has had a nice soak and has been warm enough for w few hours, he may perk up a bit. If he does, you can try feeding him. Get some plain chicken baby food. Drop a small dollop of it right on the end of his snout. Many times they will lick it off. Never leave uneaten crickets in the cage. They will bite an inactive dragon, and while the bites are tiny, they are very prone to infection. Such bites often cause a dangerous systemic infection.