Do you know what his previous care/diet/supplementation was like?
It sounds like iot may be a sign of MBD, many times beardies that are not given enough Calcium or access to UVB lighting their bones become soft, and sometimes their bones can fracture. Your beardie may have a fracture, or it may be an old fracture that healed funny. Either way, if he had low calcium levels he probably still does, i would make sure to supplement his diet, give him adequate lighting, and a trip to the vet might not be a bad idea....just in case...
-----
0.1 Bearded dragon
0.1 mexican kingsnake
1.0.2 Leopard Gecko's
0.0.1 Rose Hair Tarantula
1.0 BTS
0.0.1 Reverse Okeetee Corn
0.1 Bullmastiff
4.1 Cats