Circumcision problems. Help

My son was circumcised yesterday at 8 days old. Nothing really bothered him yesterday but today he has been cranky and having a hard time sleeping. He screams bloody murder when we change his diaper. We've been doing what we were told to do with the Vaseline so it doesn't stick to the diaper. But how long will this last?  Anything I can do to help him?  He's so pitiful. Thanks