Unknown protuberance (picture added)

Pictures might help...

 

Most likely it is the naval not completely healed. Omphalititis or Mushy Chick Syndrome comes from when the humidity is too high during incubation. The chicks usually hatch with an unhealed naval or the unabsorbed yolk sack still attached.

You should keep an eye on it as it grows but if it turns out to be a fine bird I see no reason why you couldn't breed it. And if it is a pet, so much the better for it. If your other chicks that hatched turned out fine I wouldn't do anything differently next time, it could just be a random thing too.

Best of luck, JW

 

That's what it looks like, the naval just a little unhealed. I should be fine as long as it is getting around and eating and drinking. You may want to put antibiotic or a piece of bandage or something on it if it is under a mother hen in case the nest box is dirty, but otherwise when it heals it should be alright.

 

If you don't want to let nature take it's course, I would, like I say, put whatever ointment you have on hand on, or hydrogen peroxide, then put it on a towel or preferably stick a bandage on if you have a sticky one that would stick to chick down. You can either leave it under the hen or put it in a brooder with a heat lamp, just make sure it is warm enough and you don't keep it out too long to bandage it so it doesn't chill. Then you wait. Best of luck, JW