L.N.
My daughter drank alimentum because of tummy issues. She loved it. It's supposed to be very gentle for kids. It is different, doesn't have much bubbles, and of course it tastes different. Maybe your baby needs time to get used to it. Also, don't switch from one to another formula without having him on one for at least 10 days (until he gets used to, or not). Again, while alimentum was crazy expensive, it is the only formula my daughter had no issues with.