I have an achy feeling in my ribs and back. my ct scan and blood test came back clear. but, today i have a small bruise on chest. what could it be?

Trauma?: Did you do something that may have caused the bruise even a couple of days before? If you cannot remember anything, consider an episode of particularly violent coughing. If none of these seem to ring a bell, you may have a bleeding disorder or a sensitivity to the ibuprofen. Ibuprofen can cause an increase in the bleeding time and make it easy for you to bruise. If it worsens see a doctor.