Could Deep Cough Be A Symptom Of Persistent Sickness?

I ve been diagnosed with the flu and while I m feeling stronger, still have this relentless cough (deep) that just won t quit, even with the strongest cough syrup (IC Iophen C NR). 1. The doc told me I could return to work on Thursday but if I m still coughing, is it safe to go back? 2. Is the fact that I m coughing - despite feeling better in every other way other than mild congestion - mean I m still sick? 3. When can I get back to exercise (light swimming and/or weight lifting?) 4. And, if I do go back to work Thurs, and if the cough finally goes away, should I not exercise for another week to make sure I don t relapse back to the flu, or can I get back to light exercise so long I make sure it s not causing me to get to bed later? 5. How long can I take Nyquil for? It s the only thing that s stopped the cough in order for me to get to sleep, and I usually sleep 8-10 hrs a night. Thank you!