Doubt its vaccine related... the guy that published a paper linking multiple vaccines to vitamin A toxicity (of which toewalking is a symptom) has had his other papers retracted by journals multiple times. His science is sketchy and he seems to have a strong agenda driving what he publishes, rather than a desire to find new knowledge.
Happy to cite if there is a desire to read up on this.
As for the lamb, I've heard of similar cases being about speed of growth as Kay said.
