Bearded dragon 1 rear leg/foot edema (swelling

My 7 yo bearded dragon has developed edema in one rear leg and foot that is not resolving. Ivan feel the thigh is swollen. Toes are normal. Both the exotic vet and I are mystified. He has a large 4 x 2 x 2 tank. Basking temperatures are 99 to 104° with an Arcadia 12% linear strip UVB properly distanced, overlapping heat and checked regularly with a solar meter. He gets a proper diet, collard greens, mustard greens, turnip greens, dandelion greens, arugula, escarole chicory, a little bit of butternut squash, green squash etc. Plain calcium on schedule twice a week with no D and twice a month a multivitamin from Repashy. He gets about three large dubia a week. Recent fecal is fine exotic that did complete blood work, including WBC and neutrophils and azurophils all normal. No signs of gout. She did a x-ray, no sign of fractures. Bones look good and strong. I can see this bothers him. He’s not running around as much in fact very little. Poop has been regular. We were on an anti-inflammatory for a week. It did nothing. I am really mystified and I am so frustrated. It’s the summertime so occasionally I bring him outside. I’m wondering did he get bitten by a bug and it caused a reaction? But labs are all normal. Any ideas?