Hard to believe...

My sweet little boy is crying in his crib. He use to go to sleep with no problem but for some reason these past two nights he is not having it. He went to bed fine last night, but woke up in the middle of the night and would not go back to sleep in his crib. His naps today were pretty much nonexistent. He is so tired. He fell asleep in my arms but the second I laid him in his crib he screamed. I'm letting him cry. Oh it breaks my heart! Where is my sweet easy going Xavier?!