Formula for EBF baby with milk protein sensitivity?

Has anyone found a good formula for babies with a milk protein sensitivity? Our pediatrician had us try Nutramigen and Alimentum, and baby refuses to eat either one, even mixed with breast milk. He also doesn’t prefer the taste of frozen breast milk, so I’m kind of at a loss here and I’m trying to get back to work full time where I might not be able to pump much! My boobs can’t keep up with him!

We also tried going back to Similac sensitive. He’s had a few watery poops and reflux from it. He’s never had green poop with blood, the classic dairy protein allergy symptom, but it does seem like his tummy reacts.