Cough/phlegm/lung capacity woes

I don't have the flu but doc said rest...that was Saturday. It's Tuesday and I ran for the first time and I nearly coughed up a lung. I am taking mucinex etc...but doc said I may feel crummy for a week or , yikes!, two!
I'm tired ...can't sleep well with all the coughing... but my legs felt pretty good running.

Was planning to race next weekend... sprint. But at this rate not sure I'll be up for it. And frankly if I feel like this in 2 days, I'm calling the doc back. I've never had a cold last so long and not really get any better.

Others have such suckball illnesses? Do you train/race? Cut back lots? Or just do what your body will allow without too much public humiliation (phlegm balls are not my thing) UGH!