Are Bronchial Coughs Bacterial Or Viral?

Are bronchial coughs bacterial or viral? I have some penicillin -V 400.000U that I got in Mexico. Can I take that? Penicillin is only effective on bacterial issues, correct? Also: My resting heart rate is usually 60 bpm but have been anywhere from 44-55 bpm (mostly in the upper 40 s) these last 2 days. What else could be going on? I also have an appt. set for next week - to see a gynecologist about a prolapsed uterus or bladder.