Cough and Colds equals Not feeling well

I'm not feeling well last week. I suffered from colds and severe cough. I try to medicate myself by taking robitussin DM cough syrup, It's an over-the-counter cough suppressant and expectorant in one. Dextromethorphan and Guafenisin are the active ingredients. It is a temporary relief of cough due to throat irritation from common cold, flu and inhaled irritants and It helps loosen phlegm. How can i knew it? I googled it before I use this medicine. I used this when I was in college and I think it was not effective for me today. So, I went to the hospital and look for my Pulmonologist. My Doctor asked some question like how long is my cough persist and what are the medicine that I took on. I said, its Robitussin DM. He advised me to take a antibiotic called  Co-trimoxazole (Bactrim) for 7 days. well, it helps alot. The symptoms faded and my cough disappeared in 3 days of continous taking antibiotics but i need to continue it for 7 days. I'm OK now.:) It's
time to go to the gym to lift some weights. :)