I acquired a 2-1/2 year old RIR roo today.... he seems to be in good health other than an 's'-shaped head shake that he seems to do about every 5 - 10 minutes. Additionally, I noticed some "yawning" (or "gaping") once or twice also. I have him quarantined from the other birds and will be worming with Corrid and dusting for mites.... following up with pro-biotics afterwards. Any insight or suggestions regarding this strange head shaking? Many thanks for any advice.