Oops! Forgot to update. The vet found nothing wrong with him apart from his back legs are a bit bent, but he's using them fine so shouldn't be a problem. They didn't want to xray him, which is a shame as it would have been interesting to see! But because he was improving and his bones were nice and strong feeling they felt it was a bit pointless, which I guess it was, oh well! He's burrowing, eating and pooing properly again, he ate a whole box of locusts last night, shed his skin and left a properly digested poop in his hole, so it seems whatever it is has gone. I'll remember to keep stress to a minimum and make sure the extra radiator is always on standby for night time temperatures just in case he simply prefers it warmer than the others. Thanks for all your help and advice in getting him back on his feet... I really thought I was going to lose him!