To help you with the reflux (if he has it), it is important that the position of feeding is above 45 degrees or more, almost sitting up. Never lay him on his back when he is feeding or right after you are finished with feeding because the acid from the stomach goes into the esophagus and causes pain, plus vomiting. Wait about ½ hour after feeding before laying him down. Raise the head of his crib to a 45-degree angle too so he is not flat on his back. Hoped this helped you.
I would sure he doesn't have acid reflux! But he's only a week old he shouldn't be getting no more then 4oz of milk! If he keeps eating, then yea he will throw up to make room in his belly! If if he still acts hungry I would put baby cereal 1 oz in his bottle of 4 oz of milk! Hope this helps!