Hello! My 10/29 baby has figured out the last few weeks how to sit up on his own from laying down. This week he is constantly sitting up. He has also figured out how pull himself up. Sleep time has been very challenging. he has been a pretty good naper the last few months and falls a sleep fairly easily. However, now that he can sit up and pull up sleep is hard to come by. As soon as he is laid down he sits up. he now sits in his crib and cries. What can I do to help him?