My chicks just turned three weeks old today. They are all rushing at each other. I thought maybe they were overcrowded, so I made a bigger brooder. Its basically a refrigerator box. I put stuff in there for them to do, like drew spots on the walls for them to peck at and made a little swing that they LOVE. But, they're still going at it, especially when I reach inside. They happily come straight towards me, then get mad at each other and run full speed at one another. Not really sure what else to do?