His front right leg definetly looks like it has some MBD. This is not too serious, and all you should need to do is go to the pet store, and pick up some calcium. Allow that bowl to sit in his cage, and fill it up when it’s empty. Some leos will literally eat it all, if they need it. Don’t worry about him overdosing on calcium; he knows what he needs just like when you know you need water.

For him being skinny. What is your cages set-up? What substrate, temperature, hides, etc? A pic for this would be great. Also, what is his current diet?

P.S. – he doesn’t look like he should be put to sleep.