There can be many reasons, and as a Mom we have to figure out what it is. baby might be colicky, must be feeling hot or cold, must be hungry, diaper is full. check if baby is cranky and crying when certain body part is touched then it might be paining. so check for the reason that you can think of, and if it's continuos please consult your peadtrician, kindly do not try any home remedies for a small baby.