This sounds like typical behavior, at least from my experience with my son. The teething disrupted his normal routine, and now he is off-kilter. Also, he is learning new skills every day, and isn't it more fun to explore his new-found abilities than to sleep?! When my son goes through stages like this, we have to focus on getting him back into his routine. He is likely NOT going to bed too early (read "Healthy Sleep Habits, Happy Child" - greatest book ever; it saved us!).
When he would wake up in the middle of the night, we would listen for a while to determine whether he would go to bed on his own (and trying to make sure it wasn't an abnormal cry that might indicate something requiring our urgent attention). If he was still crying after ~20 minutes, one of us would go in to make sure there wasn't something really wrong, tell him he needs to go to sleep, lay him down, give him his bink, blanket, etc. and leave. (Sometimes, I would take him out and rock him for a bit, but I tried not to do this too often.) We repeated this until he fell back to sleep. It's not easy, it's not fun, and it doesn't happen quickly at first. But after a few nights of this, he'll figure out that he can't play in the middle of the night, and his body will get back on schedule.
If there is one thing I have learned, it's that their sleeping patterns are always changing, especially the first 18 months. By and large, we stuck to our guns (yes, there were nights where I blearily scooped him up, put him in bed with us, and fell back to sleep), followed the advice of "Healthy Sleep Habits, Happy Child," and focused on keeping him on a consistent schedule. And most of the time, he is a wonderful sleeper and a very happy boy!
Good luck & God bless!
B.