For context, I work in a gas station and I have a (possibly lifelong) arm injury that makes even just moving a finger so painful it brings me to tears. I was hired there and all my coworkers and my boss know that I can't be on the floor. On good days, I'll do what I can, but the more I push, the worse the pain the next day. For that reason, I only ever work the register. I have fewer hours, but as long as the money comes in, that's all I need.
Now. The assistant manager, who is literally 5 years younger than me, still in high school, gave me a verbal warning that I should also be on the floor because “I still have one arm left” and somehow that means I'm able to do the same tasks as them, even though I literally struggle to just go pee. I tried reasoning with her that 1, the same refilling tasks that take her 5 minutes take me 30 because, again, I only have one arm, and since I would only use my good hand, I have a higher chance of injuring that one as well, which is something I don't wanna risk. Especially since my good wrist is beginning to hurt. She didn't wanna hear it so now I'm kind of stuck. I definitely will not risk further injury for a minimum wage job, and I definitely will go back to the doctor for another note that limits what I can do, but in the meantime, I don't really know what to do.
Any advice?
Oh and by the way, the manager is the one who doesn't schedule me on the floor and doesn't give me those tasks.