My baby is 4 month 3 days old. From past three days hes crying in sleep. Initially he will be silent crying, his body i cn see moving, stomach moving with every cry or breathe. Then after sometime he cries loudly. And will not stop until we hold and make him sleep. Once in daytime too it happened. But he slept immediately. It look lik he has got up from some nightmare. Why is it happening?? Anything we can do to stop this,?? Or for him to get good sleep.