I have a 3 week old chick that doesn't seemed to be growing. Her/his siblings are now twice her size. She eats well and is active for the most part. She had a couple days were she stood with her head hung low and didn't' move around much. 2 days of Poly Vi Sol seemed to work miracles. She bounced back as active as ever, but now her vent is protruding/swollen and hard. She poops fine and eats like shes starving. I've put Prep H on her twice today and switched their food out for mush made with warm water and their medicated chick feed. They LOVE it! Is there anything else I can do? When I applied the Prep H with a small Q-tip I tried to gently push her vent back in. She seemed to like it because she pushed against the Q-tip and then just stayed leaned against it. But it popped right back out (vent is pulsing) I feel so bad and worry shes in pain but she runs around fine with the other chicks. They are not pecking at her vent so I left her in with them for now (I stayed and watched for an hour). Edited to add: Her vent looked fine 2 days ago.