Hi Mary,
I just wanted to say that you definitely don't want to get rid of the daytime nap. According to my own personal sleep bible, "Sleeping Through the Night" by Jodi Mindell, a 2 year old should be getting between 10 - 12 hours of sleep at night, with a daytime nap of 1 to 2 hours, a total of 13 hours on average for the day. A few things to think about are, do you have a set bedtime routine? (It sounds like you do, but if not - that may be causing a problem.) And yes, teething or travel can screw them up for weeks during or after. So you may not really get to the cause, but the effect is night wakings. I would suggest you implement the checking routine if you haven't already. This way your son knows your there for him but aren't going to let him get up. You just go to him when he cries, reassure him until he stops crying, then tell him it's bedtime and leave the room again. Wait 5, then 10, then 15 minutes, and so on. DO this as much as you have to until he falls back asleep. It might take a few nights (I'd say 3 or 4), but he'll eventually get back on schedule. Until then, I wouldn't make any changes to his overall sleep routine because that would just put you back to the start. I swear by Jodi Mindell's book, because from the time I started to use her techniques, we've had a very successful sleep routine with my 3 year old and our twins who are 11 months. Night wakings happen, but if you deal with them, they do go away!!
Good Luck,
Tricia