Almost 2-year old hyping self up at bedtime?

My son will be 21 months old next week. Around 18 months, we started working with him falling asleep on his own. He was rocked and nursed until 15 months, and then he was primarily rocked to sleep after that. We could never do the drowsy but awake thing because if he was even remotely awake, he would cry as soon as we set him down in his crib. At 18 months, he actually would go down in his crib awake, and eventually fall asleep on his own (progress!), with either his dad or I sitting across the room. It started off taking almost an hour or more, then we got it down to a "science" of about 20-30 minutes.However, the past couple of weeks, he has been fighting it like crazy. It's been taking an hour or more, sometimes closer to two, for him to fall asleep. Our bedtime routine has remained the same. He is getting his two year molars, so that may be part of the issue. But he is so, so tired, but does things to hype himself up and then he's wide awake.For example, last night, he's super sleepy. We do our bedtime routine (bath, pjs, books). He's practically falling over, so I tell him, "this is our last book". We read the book, and he instantly walks over to his crib and tries to climb in. I put him in his crib, he lays down and pulls his blanket over him. All is going well, right? Then the babbling starts. Then the screaming. Not an upset screaming, more of a, let's see how loud I can be! Then he gets up, and he'll do a baby cage match where he runs and bounces from one crib rail to the other. How does he start off so sleepy, then all of a sudden, hypes himself up wide awake?I will also point out that he is a little behind on speech. We have had him evaluated, and they recommended speech therapy (we are just waiting for them to contact us and set up the sessions). It seems like he makes strides every day in his speech, so maybe he's just on the verge of something, and it's disrupting his sleep?I know it's sometimes hard to pinpoint an exact cause for sleep issues, I guess I'm just wondering if anyone else has had a similar experience. Once he goes down, he's usually down all night long, it's just starting to wear on us that it sometimes takes two hours for him to go down.TIA! via /r/Parenting http://ift.tt/2bM4ntj