hi, thank you for providing the brief history of you. As you have tonsilitis and coughing there will be an expected pain in the rib cage due to excessive exertion happening by muscles in connection to coughing. Coughing leads to tiring of the respiratory system and the muscles of the rib cage are a part of the respiratory system so they might get tired and fatigue leading to pain. Also, having a chest x-ray on a safer side will be good to see if any lower lobes pathology is present leading to pain. Such pain is called referred pain. As you are already onto the antibiotics your infection should come down. Trying out nebulization along with medication will help reduce muscle spam. In my clinical practice such cases are treated with a combination of drug therapy , nebulization and Breathing exercises. Regards Jay Indravadan Patel