I'm having throat and chest discomfort for almost 4 months now what's possible cause or reason of this symptoms?

An investigation of these symptoms could be evaluated by an otolaryngologist (ear, nose and throat specialist), an internist (specialist in internal medicine), a pulmonologist (specialist in pulmonary medicine), or by a family medicine doctor. The exam should include a careful history, a thorough physical exam, chest X-rays, EKG and routine blood and urine tests.

There are no useful details for a physician to interpret " throat and chest discomfort". At your age, it is unlikely to be a cardiac problem, but if you are concerned, you must see a doctor to evaluate this further. Note any relationship to exertion, associated tender points on the chest wall etc since these may help your doctor in his/her evaluation.