I think I tore a ligament in my knee

F22, 5'3", 217lbs, white. To preface, I was practicing a dance this evening and must've stepped weird because I heard a *very* loud popping sound come from the back of my knee and the next thing I knew I was on the ground and couldn't get up. I went to the ER and they x-rayed it, which didn't show any broken bones. They told me to follow up with my PCP in a week if the pain doesn't get better but my problem is... I can't walk. And I'm a nurse. I start my last semester of nursing school (RN, I'm an LPN) literally next week and I work 5 days a week. I don't know what to do but it sounds like the process of getting an MRI is lengthy. I thought about making an appointment with my PCP for tomorrow to see if there's anything I can do now rather than just try to wait for it to get better especially since I don't know if I tore my ACL or not. Thoughts? Should I be worried that this is a full-on tear since the pain is 10/10 the second I stand up or even bend my knee?