Struggling with formula—suggestions?

My baby has been breast fed since birth but we are recently trying to find a formula that he will do well on. We tried enfamil neuropro and gentlease, he wouldn’t even finish the bottle. We had a sample of Kendamil Classic and he had no issues with it. We then started mixing it with breastmilk. He was doing fine until he wasn’t. He stopped eating as much, would be extremely fussy, irregular bowel movements/constipation, horrible gas. We had to give him prune juice. Our pediatrician recommended Gerber Soothepro. We started that 2 days ago, combining it with mostly breast milk. He did fine for a bit but started acting up again, horrible gas and constipation.

It’s only 2 days in but I already want to switch. I’ve read great things about Kendamil Goat milk. Has anyone had the same experience and made the switch to goat milk? Is it too soon to switch formulas again?

I’m at a loss and I hate hearing him scream in pain. It makes me so sad.