Hello....I am not sure how old your son is but here are a few suggestions:
1. Try putting him to sleep 1-1and1/2 hours later than usual
2. Make sure he is not napping too often during the day
3. When he wakes up crying, comfort him without taking him out of the crib or saying anything but by stoking his back and laying him back down. Then leave. This is the hardest of all.
Try these especially the first one and see if that helps.
Suggestion #3 would be like to cry it out.
Some children also feel a great deal of separation anxiety when they walk up at night. He needs to learn to start comforting himself. Does he have a favorite blanket or small stuffed animal that comforts him? Have you tried playing classical music or lullabies? Does he have any toys attached to the crib he can play with if he is still in a crib? You will exhaust yourself trying to comfort him when he has been already fed and is not wet.
If you need more advice, just ask!!!