Hmm... he does look a little skinny. His spine isn't showing, but that flap of skin make me think he could use a few rats. Nate might be right about the shedding. You've only had him for five days, so I would give him a week to see if he's going to shed and if not, to try and feed him again.

In the mean time, I would suggest you find a local herp vet to give him a proper checkup. Although there are a lot of experienced people on this forum, we're not a substitute for a hands on evalution from a professional.

Good luck!