You will need to see a doctor to find out the nature of the problem that is causing your symptoms. To know for sure if this is due to a chest infection a thorough physical exam needs to be done and perhaps a chest x-ray.
Do you have any type of respiratory disease? If not, it sounds like you are just suffering from a lower respiratory infection. (Due to a cold or the like) If it continues and you are coughing up any colored sputum, I'd call your doc...you may need an antibiotic.
jleigh