Yup, both aof the previous posts just about wrapped it up.
Your fur baby needs to be heavily exercised or its just cruel to them to put them in the crate.
He defintly needs to be able to see you or he feels abandoned, you can't make him feel comfertable in his crate if he has no sense of security and while WE know in our heads things are just fine, its just bedtime your pup may not. A lot of puppies do regress once they have gotten familiar with their owners but that dosnt add up to security. Your babe went from sleeping, eating, playing 24/7 with litter mates and now his whole world revolves around you! he looks to you for direction, approval and security.
Pack mentality tells him that if he is seperated from the pack then he is as good as dead but he will get over that. Also even if he has been able to hold his potty for a certainamount of time dosnt mean its pleasant for him to do so everytime. I held it for 6 hours to vegas one time but that dosnt mean I'd ever wanna do it again, ha ha!
So exersice, let him see you from the crate, and dont try to comfort him when he is in there or he'll think you are praising him for his misbehaior. Obviously I'm not suggesting yelling at him but a firm no should be sufficient. Some dogs like a article of your dirty clothing in the crate so he has your smell with him, maybe some stuffed animals, and such! Good luck with your baby and keep us posted!