Most of phlegm is caused by increased secretion of tracheal mucosa caused by inflammatory stimulation. I suggest you go to the otolaryngology department and respiratory medicine department of the hospital to have a look and have a chest X-ray to rule out inflammation or other diseases. If there is inflammation, you can treat it according to the cause, and at the same time, you can use drugs with expectorant effect, such as Chuanbei Sydney ointment, to promote sputum discharge.