V.C.
My 2 year old son went through a phase where he cried when he woke up from his nap and cried when he woke up in the morning. He was also very clingy. I don't think that your son still being in a crib has anything to do with it. When my son was doing this, he was in a toddler bed, so he could get up, play and move freely throughout his room. As hard as this will be, maybe you should not rush to get him when he wakes up crying. He will come to always expect you to do that. I know I had a very hard time listening to my son cry for awhile and not go get him. The waking up crying will soon pass. As long as you know that he is safe, wait a short while before getting him. If you have concerns about him being in a crib and he trys to crawl out of it, then it is time to consider transferring him to a toddler bed.