I have a chick who is 36 days old and for the past two weeks, she has been losing balance and shaking her head. By shaking her head I mean that she looks like she's shivering. I have tried changing her food to give her more vitamin E thinking that that may have been the culprit, but it's been about 3 days and I have seen no changes. She is being fed Eggland's Best 19% Protein Starter-Grower Crumbles Chick Feed and previously was eating Mana-Pro Medicated Chick Starter. Her poops are normal if that's of any consequence. Does anyone know what might be going on?