Hi, Noted your history of severe coughing for 9 days, lots of phlegm on coughing, lower back ache on coughing, no headache or fever, fatigued. Your history indicates towards allergic reason as the coughing is too much and there is no fever. The lower back ache is obviously muscular as it increases on coughing thereby the muscles into action going into spasm and pain. Hence it is important to get a control over the coughing first. Since there is expectoration in the form of phlegm, this needs to be controlled. I would advise you the following: First of all consult your Doctor for proper clinical evaluation and auscultation of chest as typical sounds gives an idea about the possible cause. X-ray of the chest. Tests of blood. Tests of phlegm. Symptomatic treatment in the form of cough suppressant. Mucolytic agents to loosen the coughing. Steam helps to loosen and expel the phlegm. Antihistamine and steroid for allergy. Antibiotic if there is any evidence of infection. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. T. Chandrakant, ENT and General Surgeon