My 15 week old had just got in tona good day time napping routine, 3 decent naps and then an ok night sleep. But now the naps have just stopped. He barely has an hour at a time and will just not sleep. I put him down as normal, no changes and he just screams and screams and ends up being awake for anything from 3 hours up to 4 and by then as you can imagine he's exhausted. I just don't see why he's suddenly stopped the normal nap routine. Any help?? I do all the obvious, nappy, feed, wind etc.......