I also have a tiny americana, her name is colonel sandy. When she was about 3 days old I thought I was going to lose her, she would not eat, or drink, and all she wanted to do was sleep. I gave her a mixture of gatorade diluted with water, and gave to her with an eye dropper. Made scrambled eggs mixed with mash. Went to bed telling myself that I did all I could do, and that mother nature will run it's course. I was hoping when I got up that I would not have to bury her. (This is my first time raising chickens) I got up in the morning and she was running around eating, drinking and acting like nothing happened. She sweetest ones and loves cuddles. I wonder if she knows what I tried to do that night.
She is still the smallest of the 3. When she has had enough of the other's antics, she will get in a corner take a running start, puts her head down and rolls them over like bowling pins. It is so funny when I she her in action. She stands her ground with my delaware and wynadotte and the other americana. I would not be surprised if she ends up as the top bird. Small but tough.