I'm mom of 3 and 1/2 months old baby girl.she rolled over from supine to prone position 6 days before . for 2 or 3 days she rolled over 1 time per day.after that she is not even trying to turn left lateral side which she tried continuously before rolling over.but whenever I turn her lateral side she is rolling over and whenever I put her in tummy time she is rolling over to supine position.why she has stopped trying rolling over by herself ? she also stops giving cooing sounds frequently.she is responding whenever we calls her or speaks with her.and very rarely she gives cooing sounds nowadays...please guide me...