my daughter (now nearly 2) went through a phase of bellowing in outrage when she was put down, probably at around this age - you could tell from the tone that she wasn't distressed (and we knew she wasn't ill). Lasted about a fortnight, felt like forever at the time. She's gone through a number of different bedtime phases, we're currently in the 'chat and sing to herself for about 30 minutes before conking out' one. I would listen to the tone of the crying - does he sound distressed or cross - our daughter's cry was definitely a cross bellow. Teething is a tricky one, our daughter could be as happy as larry, no dribbling or red cheeks or any obvious signs, but the pain did seem to kick in at night, and the crying would have a different tone and I would then remember that perhaps she had been chewing her fingers a bit in the day. So pay close attention during the day and if in doubt I'd maybe give him a dose of Calpol at bedtime. I wouldn't cut back on his lunchtime nap, I think that might just make him overtired and cranky and possibly worse at bedtime. I'm absolutely no expert so just really relaying our experience which was that it was just a phase. I think they do chop and change so much, and most of the time, before, during and after, we've had no idea why!