Our three-month old son sleeps in his crib in our room.  We have a nighttime routine for him- a bath (every other night), swaddling, and a bottle.  He goes to sleep easily, and just as easily, goes into his crib with little to no problems at all.  In the first half of the night, he does fairly well, sleeping anywhere from 3 to 5 hours.  The second half of the night is a different story.  I feed him when he awakes in the midnight to 1:00 time frame.  Then, he awakes nearly every hour after that.  He usually doesn't cry, but fidgets endlessly, as though he's hungry again, whimpering and sucking his fingers.  However, when I do feed him at that time, he usually falls asleep quickly during the feed and only taking a couple of ounces.  Why is he getting up every hour?  Am I doing something wrong?  I have tried giving him a pacifier to suck on, in case he is not hungry and just wants to suck.  This does not work- he really does not seem to enjoy the pacifier, and he still whimpers and fidgets.
Please help me to see something I am missing.