Also, he might be scared for what happened when he fell (maybe he was having a bad dream and then the falling didn't help)... you might want to try the mattress method LunasMum has kindly explained to reassure him that you're there and it's ok to go to sleep and once he's confident on that he might stop waking and you can remove yourself from the room.
Yes it is true, they test limits and are more aware of things and have this AMAZING memory (they remember every word you say and when you said it) so you just keep reassuring him, setting limits with love. That is, we need to sleep in our beds, mommy and daddy are tired, here's teddy bear who'll take care of you at night... say it in the day time so he remembers during night time. You're not being soft by going to him and help him settle, you're teaching the boundarie that he sleeps inhis own bed and on your own terms. If you don't see a progress with the mattress method for a week, we could try the walk in/out method. BUt i think this whole commotion is due to him being afraid of falling off his crib again and you have to work on this,
DS jumped out of his crib on a night crissis and i talked to him a lot, told him that im always around and that babies are not supposed to climb out of their cribs, they need momy/daddy to take them out, they need to use their words and ask for out if they need. And showed him the sign for "out" of the crib. Now he makes the sign with the word too... it's just a matter of persistancy.
To answer your question, yes, sometimes the sleep is off for developmental reasons and the best thing to get them on track is consistency even though you have a couple of rough weeks when nothing seems to get better. It does, i promise.