16 years old male

In early October 2014, I had a mild cold and then after that I was coughing about 20 times a day, hard...then it reduced to about 5-15 times a day and on October 23, 2014 we went to the doctor again and she gave us the 5-day antibiotics and said that we could try to treat it with nasonex first. We did, and since then, it has reduced to 2-5 times per day (more like 2-3 now), but it still hadn't completely gone away and in these coughing fits, I usually have a few coughs, in between, I may breathe in rapidly making a noise and sometimes gag. Now two days ago, I finally started the 5-day antibiotic (az...something). Today will be my third day of taking it, and I am still down to about two times per day. But I noticed today, for the first time it also made my stomach ache...

Do I need to do anything else other than finish the antibiotic and expect it to diminish to nothing gradually?

Is there a chance I have whooping cough? I mean, my coughing "spells" don't really last for more than a few seconds, but they are strong coughs and sometimes I do end up gagging and as I said, "Breathe in really fast as a result that makes that sort of noise," and often it does mildly cause chest discomfort.