When I was 30 years old, I came down with a severe flu accompanied by a persistent cough.

It began with clear, transparent phlegm, which gradually turned yellow over the following days.

By the fifth day, I was coughing up nearly half a cup of green phlegm, which alarmed me and prompted a visit to the hospital.

After examination, the doctor diagnosed me with pneumonia and admitted me for antibiotic treatment.

Fortunately, the medication worked quickly, and I was discharged after two days.