My DS1 hasn't always been the best sleeper but we've always muddled through, and he had gotten considerably better in the last 3 months or so, and then suddenly the past 4 nights he has woken up absolutely screaming his head off to the point where I thought he must be hurt! But I can't find anything wrong? He doesn't have a temp or anything and his fine during the day just seems to be in the middle of the night? Has anyone experienced similar or have any idea what it might be?