She realized it was only water and not her regular ‘drink’.
I, too, noticed she didn’t drink anything. Meaning whatever it is, she knows water won’t do the trick. Right before the cough started, she appeared to be gagging and swallowing or something like when someone has heartburn. But we know it’s not something so simple as heartburn. Then she comes back all perky but slurred speech which means an injection of something that acts quickly.
A muscle relaxer for her throat?