I might be completely wrong here so don't hold me to it. Can you get anything from her udder? Isn't the wax yellow because it's leaking colostrum? If you can't get anything from her udder then it shouldn't be wax? I've only had one wax and she was a big mare, it covered her the whole bottom of her teat and when I took it off it was very sticky. How's she doing today?
I'm pulling for your vet being right and everything is fine she's just being dramatic.......it never hurts to think positive and hope