I recommend being
open and honest with your doctors, and asking for their advice and help.
It may be that you have an aversion to this one product, and that you may be more able to swallow a different brand or flavour. If your doctors know you're having trouble drinking those shakes, and why, they may be able to help you find a substitue.
I remember, when I was your age, they were trying to make me drink Sustagen in hospital, and I simply couldn't - it was so foul it made me feel like gagging every time. So, the dietitians did a bit of thinking, decided to try the Sustagen "pudding" instead and lo! suddenly I could eat it... and I actually really enjoyed it
. Moral: don't be afraid to admit that you're having trouble, because it may be easier to find a solution than you expect
.
Big hugs to you,
Ivy.