karen,

Thanks for your question.

I assume the chest infection was a respiratory infection such as bronchitis or pneumonia.  As you know, this usually includes severe cough which can cause a bruised, cracked, and even a broken rib.  This is a very painful situation because the rib cage moves with each breath.  I also note that you have entered this question under the category of COPD.  If you have been on steroids for your lung disease, this may cause bone loss, or osteoporosis, which raises the risk for broken bones. 

If a damaged rib is not the cause, other possibilities include a problem within your chest, such as a new area of infection or pneumonia, a collapse of a lung (called pnemothorax) which is more common in patients with COPD, or other problem with your rib. 

Because this is Heart section of HealthCentral.com, I want to add that it is unlikely that your discomfort is caused by your heart.

Because of your underlying lung disease, you should see your physician for an evaluation.  This is important because the rib discomfort can affect your ability take deep breaths, which can be detrimental depending on the severity of your COPD. 

I suggest you call for an appointment to be seen as soon as possible.  Should you develop any respiratory distress, you should go to the emergency room.

Feel better.

Martin Cane, M.D.