I'm taking azithromycin for mono and pneumonia, but now i have pain from my fingers to my arm on the left side, & a cold sweat. should i be concerned?

Give it time.: Since mono is caused by a virus, the Azithromycin was prescribed for the pneumonia. The pain in your left upper extremity and the cold sweat more than likely symptoms of the mono, though pneumonia could also result in a cold sweat. Unless you have shortness of breath, pain out of proportion, or rapid deteriorating health, complete the antibiotic course and follow-up with your prescriber.