Need advice about my Job

I'm new back into the workforce and took a job I'm way over qualified for as a receptionist at a salon. All the stylists are amazing and I work my butt off there. Problem is the owner she is never happy with my work and finds small things to pick on. Which is strange considering the condition of the place. This is no high end establishment. That being said I'm very clean person and I work extremely hard when I am there. I've been told when the owner is there I am basically supposed to be running around endlessly for hours. The whole dynamic is weird. My main issue is she is constantly asking me to do jobs that are either above my role or pay grade. I get I clean totally what I signed up for but now I'm also asked to be painting? I am worried one of my shifts she is going to ask I paint and I honestly cannot afford to get paint on my clothes? What do I say? She is super unpredictable and unprofessional. I seriously don't get paid enough for the job I do. I am the first receptionist who gets along with everyone and I guess does all the owner asks without quitting so I know I'm a rare one. At what point can I approach the owner about a raise since I'm working outside my job? Also just last week I had to confront her for not paying me for my working hours and cutting me short the nights I close late and that whole discussion was horrible and she's been taking it out on me since working me till my hands actually bled. I need this job too.