Had the flu 3 weeks ago. still have cough, congestion, increasing fatigue, muscle aches and stabbing pain between shoulder blades. should i be worried?

Chest xray: many viral illnesses can cause symptoms for weeks, but with a continued cough and pain, I would worry about developing a pneumonia. It would be wise to get a chest xray to make sure there is not a worse infection going on

See doctor : Flu can be followed by post viral cough but stabbing pain warrants detailed history, clinical examination and maybe X Ray to rule out pneumonia .

See doctor : There can be multiple reasons for pain between shoulder blades besides being related to flu . Please consult your doctor.