Thanks for your question.
Because your discomfort is effort related, it raises the possibility of heart disease. Chest discomfort due to coronary artery disease is described in many ways: burning, cramping, sharp, dull, pressing, and more. Females tend to exhibit their symptoms in more different ways than males, sometimes making it a challenge to establish a diagnosis.
I suggest you make an appointment with your physician for his evaluation of your symptoms. This will include a history, an examination, and an electrocardiogram, after which your doctor will be in the best position to determine the cause of your discomfort. He may request further testing based on his impressions.
If heart disease is ruled out, other possibilities include a gastrointestinal source such as gallbladder disease, ulcers, hiatal hernia, etc. Your lungs are also on the list of possible causes. Your doctor will work through these possibilities with you. Most of the other causes are less serious than heart disease and can wait until the heart has been ruled out as the source.
So call for an appointment as soon as possible. In the mean time, I would curtail your activity until this puzzle is sorted out.
Best wishes and feel better.
Martin Cane, M.D.