Signs of autism in infants?

My granddaughter is 7 months old and will just cry, well it's actually screaming for no reason at all. Her motor skills are'nt as good as her twin brothers. Also when she is sleeping she will just cry in her sleep,eyes closed but crying even though she's fed, dry diaper and nothing is wrong. Also during the day she will have screaming fits. Just looking for some symptoms or signs to know what we need to do. Thanks to all!