What Causes Pain In Lungs While Coughing?

I started with a cold on Tues.17th, last week. I ve been coughing out of control. On Saturday 21st I saw my PCP and was given amoxillin 875 for 10days. I m getting very sharp pain on my left side back lung area when I cough? Should I return to the Dr. For further evaluation. Btw.. The switched my abx. To Z-pack yesterday!