Welcome. The head twitching sounds like a potential respiratory issue.
You are great! Well, for several days it (Maran, I use she but not sure yet if it is a pullet or cockerel) has been lethargic and keeping its distance from others and it's comb looks pale, and sometimes tqitches its head. It is still eating and drinking but sometimes seems like it requires prompting to feed. This morning it was laying down and someone scared her and when she got up she seemed off balance and almost fell back but then picked up at a run just fine.
Have checked the vent and it is normal and checked the body for mites but no sign of injury or mites.
The first day we noticed that we isolated it in the garage for a couple of days and added vitamins and probiotics to the water but it seemed stationary and was still eating and drinking so we moved it back into the coop with the others and there has been no improvement but also no worsening that we can tell.
All 12 came from a local person who breeds chickens and we're not vaccinated. We have been adding apple cider vinegar to the water and have medicated starter feed for them.
Perhaps it is worth mentioning that the other white Maran had the same symptoms about a week before this one but started looking normal after a couple of days so we reintegrated it and it has been normal since. None of the other birds seem to have problems.
Thank you!