He had done this for two nights in a row now. We go in, try to soothe, give milk, rock, etc. Have tried letting him fret for 10 minutes at a time. It just goes on. He is 18 months and has never done anything like this before. His sleeping was erratic for a long time but it was always just frequent wakings that were very short. He is just getting over a cold but seemed to be really fine as far as breathing went tonight (it is still 3:40 am here, I can't go back to sleep - again!) Any suggestions?