It's possible that he has a slipped tendon or other leg issue. Vitamins with trace minerals could possibly help, but this is a very hard thing to make better. Here is some reading about vitamins and splinting...
Curled under toes into a claw can be due to a vitamin B2 (defiency,) but toes curled sideways may be genetric or due to incubator temperatures flucuating.
He might be a little weaker or meeker. What you are doing is probably the best for him. Mareks can present symptoms at this age, but usually is later. Vitamins, probiotics, and some egg may help him catch up.
Pictures and videos can help to see what you are seeing. Vitamins with trace minerals may help if he has a deficiency. How old is he? Were his toes curled under or just crooked to the side? Is he eating and drinking enough? Was he vaccinated for Mareks disease?