Has anyone had to switch their baby to soy formula?

After 4 months of pain and multiple formulas we've come to the conclusion (with the doctor) that my baby is mostly likely incapable of digesting lactose and casin.

We're starting a whey based formula today to see if that works.

If she has a bad reaction to it we'll have to give her soy.

She's 4 months. She's been on probiotics since she was 2 weeks, they help A LOT, but not enough.

Has anyone had any experience with soy formula after your baby was unable to drink dairy?

Please do not respond if you're going to be judgmental, it's not your kid that's throwing up twice a day and up all night screaming with gas pain.