5 mo. old wakes every 2-3 hrs at night Help!

My son is now 5 months old about a month ago we transitioned him into his crib. For the first few nights he did great slept almost a 5 hr stretch before waking up. Now he doesn't go more than 2 or 3 hours before waking up and needing to be picked up or have his binky put back in his mouth. By 3am he generally won't go back to sleep and ends up in bed with me, which I would prefer to break now before he gets to used too it. Any tips or ideas how I can help him sleep longer besides cry it out (I'm a marshmallow when it comes to him and can't stand to listen to him cry)?