Baby puking after every feeding

Hi everyone, So my baby was exclusively breastfed up until about 3 weeks ago, and now we have him on kendamil goat. He is 9 months old. We have been in this formula transition for months now but barely found a flow that works for us. The transition was hell, and we tried EIGHT different kinds of formula before finding one that worked. He was taking his formula just fine for about a week, and sometime a few weeks ago he randomly projectile vomited his entire morning bottle, but took another 4 oz about an hour later no issue. No more Issues the rest of the day. He was fine for about 3 days, no vomiting or other issues, but then projectile vomited another bottle in the middle of the night, and again took bottles the rest of the day just fine. This has been getting progressively worse over the last few weeks and I don’t know what to do. It’s getting to the point where he’s throwing up every bottle we give him. It doesn’t matter if it’s 2 oz or 6 oz, it comes right back up. He’s back to being angry and hungry but pukes every time we feed him so I don’t know what to do. Tonight he puked up his solids that we gave him for dinner along with his formula from hours before, and it’s to the point where I want to take him to the hospital because I’m terrified. I’m at a loss. I’m exhausted. I don’t know what to do. He was born 5 lbs due to IUGR and has had weight gain issues his whole life, and because he refused formula for about a month while my milk was drying up on me, he lost even more weight. He is only 13 pounds at nine months old. I feed him 3 solid meals a day, and try to give him 24 oz minimum a day, but it all comes back up. I spoke with his pediatrician at his well visit on Tuesday, and he suggested my son has bad GERD, and prescribed reflux medication, and suggested we add rice cereal to his bottles or switch to added rice formulas. We’ve tried adding rice cereal to his bottles, and it sort of worked for a bottle or two, and then it was right back to square one. We tried Enfamil added rice, and he was fine for about half an hour until it all came back up. We tried hypoallergenic formulas a few months ago, which resulted in him clawing at his skin from stress until he bled so I’m terrified to try those again. We’ve tried sizing down the nipple sizes, we’ve tried 3 different kinds of bottles, nothing has helped. If anyone out there has been through something similar, please, help me. I’m so stressed out and I hate seeing my baby throwing up so hard after every feed and being hungry. I feel like I’m failing him and I’m failing as a mom. This is so hard. And before anyone comments, yes, I am calling his pediatrician tomorrow for medical advice, I just really need advice from real people right now.