when to change to hungry milk?

I have a 5 week old boy who drains a 8oz bottle nearly every feed and has it topped up with water and is still never fulfilled, ever since birth he has guzzled his milk. Between feeds he never settles and takes ages to sleep, when he does he only sleeps for about 30 mins to an hr if that. At night he wants to feed every 2 1/2 to 3 hrs and still does not settle he never seems content. I was considering changing his milk to hungry milk at night to see if it fulfills him and he can settle better but am worried it might make his stomach bad as I had to change him to comfort milk because he suffered with severe wind and have been advised that this could happen. Any advice would be greatly appreciated as he never seems to get much rest which means neither does mommy