I have seven Silkie chicks, they are 7 weeks old and were broody hatched. I picked them up locally at 1 week old. They have been on Dumor and Purina (medicated) Chick starter since I got them, with an occasional hard boiled egg treat. But nothing else besides fresh water. They are secluded in their own new brooder box. All chicks have good weight, good appetite, are drinking water, normal feces, and feather development looks great. I see a normal pecking order within the 7 chicks with no one being targeted, etc. All of this suggests healthy active chicks. However, over the past two weeks I have noticed two of the chicks exhibiting (infrequently) a tilting of the head to one side, then quickly doing it again and again. Its like watching deja vu. Not shaking the head, and its not that jerky of a movement, like a glide until the head is parallel to the ground, then pops back up to do it again. I see no respiratory issues, no water discharge from nostril or eye , just a tilt and repeat 3-6 times, then they are fine. I can't find anything online that describes this malady, but am thinking some sort of dietary deficiency or ear infections? Thank you for any advice!!!