Is he on regular formula? I have heard that some reflux babies start showing their lactose intollerance as they get food, because they know that they have another option of food and will start refusing the formula. I would try a different formula. My son did the same thing and he was only taking 6 oz a day, but he was a big boy and I didn’t worry (looking back, I would have switched to a different formula). Once he turned one, he refused whole milk and would only drink Yo-J (yogurt and juice) so then I got the idea to try to give him milk with Acidophilus (good bacteria that helps with digestion that’s found in yogurt) added and he loves it (oh, he hated soy too). The main thing about formula is the extra iron in it, so I’d try to find another formula that works.