Opinions needed

Okay, so I just started this job with the position to bring food to customers and ensure their satisfaction. The main complaint I get is that I spend too much time around the kitchen, waiting for food to come out to be served. The thing is, I have checked on all customers in the restaurant and all are satisfied. Who constantly wants someone coming up to them while their trying to eat?! The workers talk about me behind my back (I know because I can hear them and when I'm around, they're all quiet) and also, the person serving with me is also standing by the kitchen, texting and eating right in front of their face, yet nothing was said to her. They just changed my position to dishwasher without my knowledge or even getting my side of the story. Another part of our job is to sweep and mop the lobby. I swept so my partner can mop because I had to leave for a counseling appointment. Meanwhile, she is over at the bar eating when we arent supossed to do that until we are done cleaning. Also, I'm leaving back for my last semester of college in about 2 weeks. My question is, should I take this treatment and stick it out, or just quit now and focus on going back to school? I also have a work study job (when I return to school) and a writing job so I won't be totally broke if I were to quit. I'm sorry that this sounds so childish. but I just don't appreciate how I was treated today..