2 week old chick became not steady on the feet stretching one leg to the site, limping,falling - Marek's?

[CanadaEh]

1 of 33 2-week old chicks in the brooder became not steady on the feet stretching one leg to the site, limping,falling, being stepped on. Also opening mouth often (but not yawning).
Is it an injury or Marek's? Can Marek's affect 2-week old chicks and what would be the symptoms? We do have chickens in the outside coop and run.

 

[oldhenlikesdogs]

Mareks generally doesn't show up until 6 weeks or older. 2 weeks is too young. I might try some poultry vitamins in case it's a slipped tendon, or the start of another deficiency.