Newborn not sleeping well

Our newborn son is 3 weeks old.  He has reflux pretty bad, and we 'believe' we may also be dealing with colic.  I know all babies are different, but our first son would sleep the entire day and night.  We would literally have to wake him up for feedings.  We were so spoiled from our first, and we are at a loss as to how to deal with the baby's lack of sleep.  Today the baby was awake for 12 of 13 hours during the day.  I can't imagine it's normal for a baby to NOT sleep!  Also, his lack of sleep isn't the most concerning issue....it's the fact that he cries most of the time when he's awake.  He constantly acts hungry, even though he is gaining good weight.  However, I have to be thankful he sleeps well at night.  He's up twice to eat, but otherwise sleeps all night.  Any idea/advice?  I feel so helpless!  Thanks!!