reflux 5 week old excessively spitting up & fussy


So my 5 week old was diagnosed with reflux about a week & a half ago. he's now on zantac, which doesn't seem to be helping. he's still arching his back sometimes & making the chewy & sour faces. I know zantac doesn't "cure" reflux, but he still seerms uncomfortable. he's also been spitting up almost every burp, which is every 0.5-1oz. he eats 4oz bottles, but still seems hungry when he's done. if I give him another oz, he spits it all up. he also freaks out every time I burp him. like, screaming at the top of his lungs sometimes freaking out. I don't know how to help him and it's breaking my heart. I have a doctor appointment tomorrow, but if anyone has had the same experience, please give me your advice! he's on Similac total comfort if that matters. he was on supplementation, which made him gassy & runny poops. then we trailed Enfamil soy to see if there was an intolerance, but that made him constipated. now on Similac total comfort. poops are good and not gassy anymore, but sometimes gets a little backed up. any help is appreciated!!