What the hell can it be?

 so I’m currently a teacher and I’m currently very sick I the past week have a deep cough that makes me vomit and brings up a lot of green mucus, a stuffy nose and a raspy throat and partially losing. My voice have never gotten a fever and was tested for Covid, flu RSV and strep, and all came back negative, now being told they wanna test me for mono but how the hell would I catch mono?  I’m just so frustrated. Has anyone ever had mono or has anyone have any of these symptoms currently