Courtesy or required

Hi. So I’m kind of new to the workforce and I’m in the medical field. Been at this company 7 months and I need to call off for some personal things. My boss is saying that if no one can cover my shift then I’d still need to come in. Am I required to find someone to cover my shift before calling off or is it the job of the company to find someone? I’m over here scrambling asking coworkers to work that shift for me and everyone is saying no 😭😭😭 my mom told me it’s courteous to find someone but not required? Is this true?? Idk what to do I really need those 2 days off