It's not unusual, and it will take some experimenting to find things that you can tolerate. Two years post-op and I still have a pretty low tolerance for sweet stuff, natural or artificial.
I often balanced out my protein drinks with unsweetened and unflavored protein powder. You can also try unsweetened/unflavored protein powder mixed into things like broth or other savory liquids. If you were several weeks post-op I'd suggest adding espresso powder to the vanilla shakes to provide a bitter counter-balance. Lemon juice added to vanilla shakes can help too. Of course, before you add things like espresso or acids from citrus and such, I'd check with your dietician/doctor. Some clinics have some very specific rules about such things.
Everyone is a bit different. My taste for some things has never returned (such as meat and some sweet things).
The other thing is, that sometimes you have to do things that suck during this process, but it's usually temporary. It's a prescription, and sometimes we have to gut through prescriptions, but we do it. I hated drinking super-sweet protein shakes, but I knew it was in my best interest to get through them.
Stay as true as you can to the post-op process. You can do it!
R
