Shift Day Mix-Up

Today was supposed to be my day off, but some new nurse named Lisa called in sick. My manager couldn't find anyone else available and asked me to fill her spot. I agreed under the condition that she'd take over my shift next week when I wanted time off for a family event. But now here we are, and Lisa hasn't shown up yet. It's been a long day with lots of sick patients, and I'm starting to feel guilty about not being there for them. Plus, every time the phone rings, my heart races because I fear it might be a message from HR or my manager canceling my leave and asking me to work an extra week. This is exactly why I don't take on additional shifts; things always end up more complicated than they start.