Three weeks ago I was diagnosed with the flu ,
You should be tested further
Normally we wouldn't expect complications three weeks after the diagnosis. There is a concerning point in your description namely the pleuritic chest pain ("hurts to breath"). An infectious complication seems unlikely due to the long time since the diagnosis but other types of complications are possible like the following:
- broken rib
- intercostal muscular strain (due to coughing)
Most patients who complain of similar symptoms do not usually have anything serious but symptoms like yours warrant investigation to exclude the more serious causes. Clinical examination and a chest X-ray is enough for most patients.
I hope I've answered your question.
Please let me know if you need further assistance.
Dr. Panagiotis Zografakis