My dad is 64 and has had a fever and cough for the past four days. We saw a doctor who suggested a COVID test, but it came back negative. We met with the doctor again and were told to do more tests. Today, we got the reports, and his CRP level is at 32 mglitre, and the X-ray shows a mild haziness in the lower left zone of his chest. I'm really concerned and wondering what could be causing these symptoms?