Honestly, he's in fairly poor condition, and with those glass marbles harboring waste and you not even having a filter, I'd say get him out of that tank right now.
If I were you, I'd put him in a temporary container, probably of hard plastic if you don't have a spare tank. Use cold dechlorinated water and do water changes DAILY. This will at least get him in a cleaner environment than the one he's in now. He has exposed bones on his foot, and it appears that he also has breaches in his slime coat and skin. As long as he's in that poor environment, he's going to be highly at risk to even more serious infections,
so seriously get him out of that tank.
As for food, try feeding him earthworms. Blood worms, while great for juvies, aren't enough for an adult axolotl. Earthworms are the most nutritious and they're very simple. He probably won't have much of an appetite right now, but keep trying. He's thin and he's fighting illness, so he needs as much as he can get.
You need to get a filter and clean out your tank. I personally think you should start from scratch; Drain your tank completely, remove the marbles, wipe down the sides and bottom. If you want to have a substrate, make sure it's a silica-based sand that has been pre-rinsed thoroughly. Let your tank cycle while your little guy is in the separate container, and when he's well enough to return to the tank, continue to do daily partial water changes until the cycling is done.
I'm not gonna lie, he's in bad shape. Not the worst I've seen, but he's not doing too well