Also-- check the baby's toes (and in boys their special part) to make sure hair isn't wrapped around.
Julia was uncharacteristically fussy for a few days. upon REALLY close inspection of her toes, this was likely the cause. The hair was wrapped around so tightly that we had to take her to urgent care to make sure there wasn't any left imbedded in her toes. It was difficult to spot because it was blond hair and her toes didn't change colors from it. The urgent care doc had to make tiny incisions in the offending toes to make sure all the hair bands were broken. It's common enough that the medical computer system has a code for it -- hair ligature of the toe.