Late Night Feedings?

So my son is 6 months old.. he does not wake up often but he will whine around 2AM for like an ounce or 2 of milk and go right back to sleep. His dr suggested patting his back..giving him water..and simply letting him cry but not to give him the milk. None of those have worked.. any advice or comments would be helpful. I'm not a FTM but this is the first I've heard a doctor say those things. He's 19 lbs.. and does eat homemade solids..thanks ladies!