A few months ago my son was waking up about every 2-3 hours at night, he would normally sleep 11 hours straight. It turned out he was teething. I know you said your little one got two teeth a few weeks ago but he could be getting more. When I was having this problem someone mentioned that when babies teeth the pain is worse at night because of the blood flow while they are laying down. It became very clear that my son was teething and I gave him Mortin to deal with the inflammation and he started sleeping through the night again. I'm not saying you should just give your little one Motrin and see what happens but you might want to consider that he might be teething again. If that's the case, I highly recommend Motrin instead of Tylenol. It works longer and doesn't just deal with the pain but also the inflammation.