Oversupply? Reflux?

Misa418

My ds is super gassy and has been crying while nursing. I went to a  LC and she said I have an oversupply and to start block feeding. I have been doing that and it has been helping somewhat, but ds will unlatch after 5 or 10 minutes and start screaming. He usually won't latch back on after that, but if he does, he is very fussy and won't stay latched for very long. We started him on zantac two days ago, but so far it hasn't made a difference, though it is still early. It is heartbreaking to see him so hungry, but not able to eat. The odd part is he can usually take my bm in a bottle without too much difficulty. I am so confused! Is the screaming from reflux/pain or frustration because the bottle is easier to get milk from? I have no idea what to do. Any suggestions?

He is 7 weeks old and I have already cut out dairy, soy and eggs.