Definition
In a pickle, in a mess, in the soup.
How People Actually Use It
To be in a fix simply means to be in a confusing or frustrating situation. To be in a dilemma
"Justina's car still won't start and there was no way she was going to demean herself by struggling for a bus at the crowdy bus station.She was clearly in a fix as she was already fifteen minutes late for her job interview."
Source: Urban Dictionary