LO eating less 🥺🥺🥺

My lo has been eating less somethings skip feedings. He won’t even take the bottle it makes him gag he goes from 4-6 hours without eating. Is it normal his formula fed and was doing enfamil a.r for spit up but i dont know I think that formula was to think and smells way stronger so I decided to do enfamil yellow and he’s been doing better stills gags and don’t want to take all ounces but doing a little better. I told his pediatrician and said it was ok that’s all he says so guess what I got a new ped. Anyway also he eats and he poops right away. He would go from pooling once a day to skipping a day now he does 2-3 poops a day is it normal? Anybody’s else lo not eating same way like eating less? Talk to me!!! I feel so bad when he doesn’t want to eat