Hello,
Is he under your care now?
I do not think that is an injury, it looks to me to be metabolic bone disease or possibly an impaction.
Normally, a spinal injury would not look like that. It would not be appearing like a lump but more crooked in appearance. The tail tip or last 1/3rd of the tail would most likely be darkened due to stress or pain as well.
It is possible that he is older than they have told you if he was kept improperly at the pet store or the previous owner's home.
For starters, I would replace the calcisand as it is calcium based & NOT digestible at all. Unfortunately, it clumps up when it gets wet & will cause terrible impactions. I would put in paper towels or a nice soft towel right now for him.
He will need a much stronger
UVB light. I am going to recommend either the Megaray or the T-rex active UV heat either one are great. They are mercury vapor bulbs & will blast him with UVB exposure.
You can get the Megaray here:
http://www.reptileuv.com/megaray-products.php
You can get the T-rex here:
http://www.reptilesupply.com/index.php?cPath=26_33
The Solar Glo is fine, as well.
Then, you should try to get some liquid calcium, if possible. Which calcium are you using?
What other type of feeders are you using for him? I would limit the waxworms due to their higher fat content. They are fine for occasional treats, but not as staples. Try appropriately sized crickets, roaches, phoenix worms, or butterworms.
What type of thermometer are you using to measure the temps? A stick on type, a digital probe or a temp gun? The basking temps need to be 95-110 & the cool side around 78-82. Otherwise, if he is not warm enough, he cannot digest his food properly. If you are using a stick on type of thermometer, they are not very accurate. You will need to get either a digital probe or a temp gun for better readings. If the temperatures are good for him, then he wont overheat. Since he cannot move away very well, make the basking temperatures no higher than 98 or so. That should be sufficient for him, & allow for comfort for most of the day for him.
Please let us know how he is doing.
Tracie