I recently got a new job working at a fast food restaurant out of necessity, and was very vocal in the interview that I needed to leave at or before 9pm to get home, because I am a university student and wake up early to get all of my studying and work done. I was reassured that this was fine, and even encouraged to give them shift times that would work best with my schedule. So my second day, on which I was scheduled to work until 9pm, I left at 9pm exactly. My boss even texted to ask me to confirm that I had left at 9pm that next morning.
The next day, I went in for the same scheduled shift, and was again supposed to work until 9pm. Due to me being in recovery from an ED, I have pretty weird and erratic intestinal issues, and during my shift, about two hours before it was supposed to end, I had to use the restroom, so I let a coworker know and I went to the restroom for about 20 minutes.
When I came back, and was about to walk into my station, a different manager from the one interviewed me stopped me and asked where I was and how long I'd been gone, which I told her. She at first told me to clock out and go home, and when I was confused, she said that being in the restroom for 20 minutes was unacceptable to her, that and to let her know next time so that she could “watch for how long I was gone.” She was upset that my coworkers were cleaning without me, but I argued that I had let them know where I was going, and that I needed to go. She seemed upset by this but decided not to make me clock out.
We walked back to my station, and then she asked what time I had left the night before, which I told her was 9pm. She said that I wasn't supposed to leave at 9pm, even though I was scheduled to leave at that time, and that my coworkers had to clean up by themselves, and that I was supposed to stay with my coworkers and clean up with them as well until they were done closing. I asked if they were also scheduled until 9pm like me, but they were not. They were scheduled until 9:30 and knew they were scheduled to close. So me staying as long as they were, while only being scheduled until 9, when I had even communicated in the interview that I needed to be home shortly after then, didn't make any sense to me, but she said that was what I -had- to do.
I stayed and helped clean, but that really stuck with me, especially since we stayed until almost 10, and a coworker had previously told me that management wanted all employees out of the space by 9:30 at the latest.
What can I do in this situation? It feels wrong that this wasn't communicated to me before hand, and I wouldn't have agreed to a shift that ended later than 9 if I'd known about this, and I also don't want management to be micro-managing my every trip to the bathroom. Please help.