4 week old silkie chicks pecking? And sneezing

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I have 2 silkie chicks that I hatched almost 4 weeks ago. I adore them but the last few days they've started pecking me constantly and about half the time it hurts a bit. Is there any way to teach them not to peck me? Or at least not so often? Right now they're small enough that it's not a big deal but I don't really want them pecking me constantly as adults.

Also, the larger of the two acts a bit aggressive? Very roo-like. Running at my hand and stopping at the last second with wings slightly extended and posture fairly erect. He/she has been doing this for about 2 weeks but it's getting more consistent. teenage moodiness maybe? Just curious if it's common behavior.

Also, they both sneeze. Well, more like clear their nostrils. Is that common? there's no discharge (other than a little snot being blown out when they clear their nostrils) and I've looked into all the respiratory illnesses and they don't have any of the other symptoms for any of them. they just sneeze or clear their nostrils regularly throughout the day. I don't use any shavings or anything for bedding. I have old cloth napkins that I line their brooder with for easy cleaning.

 

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Oh, they also act like they're starving all the time. I always keep their feeder full, it never runs out and I make sure to keep it clean. I'm still feeding them chick starter. Do I need to switch? They are eating it but really quickly. My barred rocks didn't eat so much at their age so maybe I'm just used to a different breeds eating habits. They also eat their grit like it's a treat. I'm afraid they'll overdo it so I'm rationing their grit every day. Should I just give them free access?

All these questions and I'm starting to feel like an overprotective parent LOL