Yeah, I forgot to comment on that too, there is no "Dwarf" Bearded Dragon, just the Rankins Dragon, which he is not (they have very distinct markings and body shapes). My guess is he is just a normal central dragon who had his growth stunted by bad husbandry, probably inadequate UVB/UVA light and a poor diet/supplementations. But he's beautiful!
Yes, Dragon's do have a lymph system, that's why I first mentioned an infection. I would assume that as Tracie said, if he get's blood work done it's going to show a systemic infection, impaired kidney function or disease, or both. The fact that it's a bilateral swelling like that is what points me towards kidney involvement, as the they do swell quite a bit in renal disease, and they can actually put pressure on the area and fill the area around them with fluid, and it's definitely fluid because it's soft to the touch...but it could also be an infection of the synovial fluid in and around the joint capsules. Either way he needs an x-ray/ultrasound and blood work, and a needle aspiration of the fluid to see what's in it.
Hopefully it's just an infection that can be treated with antibiotics (do have them do a culture of the fluid drawn from the area before just putting him on Baytril, lol, that's their go-to and it's not going to treat EVERY bacterial infection), or some renal disease that can be corrected with fluids and medications...I'd keep him as
hydrated as you possibly can by giving fluids several times a day by mouth..
<<<< probably safer to hydrate by giving water rich berries and the likes of deseeded water melon , less chance of his aspirating water if giving water by syringe or eyedropper (too fast and flooding his mouth)..