Lexie is 19 months too and has always been a fantastic sleeper, but has been a shocker in the past few weeks......I have put it down to teeth (final ones coming through) adn also an ear infection......

Have you had his ears checked out? Has he had a cold recently.

And I hear you on the "not ready for 1 day sleep yet." Olivia was very much like this. But when she hit 17 months I had Charlie as a newborn, so to be honest it was weasier to just have her on one sleep. I was doubtful at first, but ended up keeping her up until about 11.30am by giving her an early lunch & then popping her into bed. Then she started sleeping brilliantly at lunchtimes, for hours, giving me loads of time to spend with Charlie.

So it is maybe worthwhile biting the bullet & chaning to one day sleep?