Metabolic Bone Disease?

[Aimee]

Hi everyone. I really hope someone can help me out...

For the past two days I've noticed one of my african dwarfies holding his hind legs in a way that looks quite unnatural. He also seems slightly lethargic, not showing much interest during feeding time.

His movements seem normal and unhindered...it's just when he's sitting still that this happens.

Diet consists primarily of frozen bloodworms with occasional brine shrimp. I try mixing commercial frog pellets in each feeding, but I've never actually seen any (I have 5 frogs total) successfuly eat any.

Could this be metabolic bone disease brought on from a lack of calcium in the diet?

Water parameters are fine: 0 ammonia, 0 nitrite, 20-40 nitrate, temp of 74-80 F

What do you guys think? He really doesn't seem very happy...