The proper lighting and vitamins are most important during growth and development. Since this guy never got the correct care he has calicium deficiency and his bone growth was impaired. You can improve his current husbandry but much of the damage is already done. Sorry

I periodically dust all my baby and adult dragons food with herpvite and calcium powder from Rep-Cal as well as providing two different sources of UV bulbs (Mercury Vapor and Reptisun 10.0). I also routinely keep them outside in screen cages to get the best light/UV there is.

That and a variety of foods with a staple of crickets and assorted greens and occasional treats(worms) such as supermealworms, silkworms or Phoenix worms .

This may not reverse all the damage but it certainly couldnt hurt.
If you ever need some beardie advice feel free to contact me via PM or email.
I have been keeping and breeding beardies for over 12 years and would be more than happy to help out.