I have had a cold for 3 weeks.was started on a z-pack 3 days ago. for a few days, have been having sharp pain on right ribcage when i cough or breathe?

Aspirin, H2O2 Humidi: For upper respiratory infections like cold and flu (but also serious infections like pneumonia) I recommend using a humidifier, filled with one bottle of hydrogen peroxide, and two bottles of water. That gives you a 1% solution of aerosolized peroxide, which kills the pathogens on contact, and breaks down into carbon dioxide and water. Your chest pain is caused by pleurisy--treatment is aspirin.