I Recently Came Down With What I Believe To Be

I recently came down with what I believe to be the flu--fever between 100.5 and 101.5, mild cough, fatigue, and body aches. 3 days later, my fever has subsided along with the fatigue and body aches; however, my cough has gotten worse, and it is now very painful taking deep breaths. The pain is in my lower throat and instantly triggers me to cough. My coughs have been dry and painless; it is the actual deep breathing prior to that causes the pain. I had also abruptly awoken from sleep numerous times last night due to taking deep breaths and feeling pain. My concern is whether the flu is developing into something more serious and when I should take further action, or if this is another symptom that should pass. Please help!