Oh, I really could have written your post not that long ago! About 3 weeks in fact! Here is my tale! We're still working through some things, but it has gotten a LOT better!
https://babywhispererforums.com/index.php?topic=104971.0;allGive your LO PLENTY of A time to practice those new skills! I would spend 30 minutes just letting her stand up, helping her sit down, go to lying position, over and over. Good news is, she can get herself down now too!
Now that they are more mobile, the wind down is even more important. Our wind down can last up to 30 minutes now for a nap. This means, the wind down starts before your LO shows tired signs. This helps calm the muscles and relax a bit before laying down in the crib. Then when he shows the tired signs during the wind down, he is more likely to give a clear signal and be rested enough to go to sleep.
I would caution against AP right now. A teeny tiny bit for a nap or two won't hurt, but too much and it'll be hard to get him out of the habit. I never AP'd until my LO learned these new skills. Luckily we were able to get her out of it fairly quickly, but it was a nice wake up call when I realized I had AP'd her so her naps were not as good.
Do you have Tracy's 3rd book? I ask because the details on PU/PD are much more detailed than in the first book.
HTH!
I'm still working through these too, but now that I'm on the other side, I definitely see the long wind down is key!