If the brooder is to warm or they arent drinking enough they can get pasty butt or get a blockage inside and they might try to roll around to try to get it out maybe? Try some electrolyte water to hydrate them?
Adding electrolytes to their water daily for their first week or so will prevent pasty butt-- my hatchery recommended this to me, and it did work- no pasty butt. Now I give them electrolytes once a week for maintenance. I bought it at the hatchery but i've seen it in tractor supply as well.