Your DS sounds very much like mine, who is 14 months. He does almost the exact same things. I have always just put it down to him waking slightly in the night like we all do, but being unable to put himself back to sleep without nursing, and therefore has to root around and cry out for me. I may be wrong of course (and he does have tummy troubles too which complicates things). Could the same be true in your son's case?