What could make my mom sick so long?

My mom had a flu and it has been over a month 5 weeks and it finally went down but she still feels dizzy and weak. We took her to a doctor, hospital for all check ups, and she still isn’t doing better. They just said it was a virus and prescribed ibuprofen. Now she can hardly eat and can’t hold down food…and we are taking her back to the doctor for a follow up. What the hell could be wrong? I’m starting to really worry….

Her friends and our family has been bringing her food since she’s been in bed for the past few weeks too sick to get up. My dad said to no longer take food from anyone that’s not our family just in case because we never know as harsh as it sounds.