Could use some more information. You said he cries all the time? What do you mean - all day long, or only at night after he wakes up?
How long of a nap does he take during the day?
What do you do to help him get back to sleep at night?
Does he eat well? or have any problems after eating?
And yes, Rockrose is right - do check with your doc. Make sure that nothing is physically wrong with him.
Has he had his one year well-check yet? If not, he's due, and this would be something your pediatrician would want to know.
Best wishes.