I know for Walgreens you have to work once a month to stay on payroll. It's a pain if you get kicked off. Luckily, I have an agreement with pharmacy manager at a store where I work that if I can't pick up a shift every month somewhere, he'll give me one.
Are there any other stores in the area around your school? If so, try contacting their pharmacy managers and ask to work a weekend shift however often to keep you active. If you can fix that up, I would personally call the store manager and explain the situation....if you haven't already.