Hope that you did get the baby checked out and that he is now fine.
Babies do cry for all sorts of reasons, but if he does cry constantly, it is always best to get him checked out.
A baby cannot tell you what is wrong with him, and the only way he is able to communicate to you that something is not right is by crying. They can cry if they have an uncomfortable bottom, if it is sore have a wet or soiled nappy, feel hungry, wind in their tummy, ear pain. A baby with ear problems will rub his ears.
Hope all is well now and sorry that your post wasn't responded to much earlier.
I would get him checked out as he had the vaccinations before he started this behavior.It may be cholic they do get it at this age .How is he eating is he breast fed ? Don't get angry he cant help it best find out why .I see this post is a couple of weeks old ,how is he doing now ?