Silent reflux

I think my son may have silent reflux. He's 5 weeks 3 days and since day one he screamed and cried all night. I breastfeed for the first 5 weeks but started supplementing with pumped milk after 2 weeks because he had lost a lot of weight. He is gaining very we'll now. I developed mastitis two days ago so I started giving him formula because i don't want the antibiotics in his belly. He's on baby's only lactose relief. But he constantly grunts and moans, very gassy pulls his legs up. Screams when he crys and turns red/ same when he's pooping. We had his stool tested for blood to see if dairy is an issue but there was no blood 3 times. He's breathes heavy when taking the bottle he sounds congested. Gets the hiccups a lot and sneezes at least a few times a day. He only takes 1-2 ounces at a time and then stops, but will take 4 ounces over the course of an hour. Does this sound like silent reflux and if so does the nat phos cure it or just help the symptoms subside? Please help