Feeling of trapped wind and chest pressure after vigorous exercise (going up medium speed two huge flights of stairs) and very tired?

Multiple possible. There are many possibilities as cause of shortness of breath. At your age is not likely cardiac unless you have some underlying known heart disease or heart valve problem. Poor cardiovascular fitness can cause this from to sedentary life style; Possible underlying lung problem such as asthma or pulmonary embolus. See your doctor for evaluation.
Chest pressure. From deconditioning to pulmonary embolism the differential diagnosis is vast ;needs formal consultative evaluation and management, not possible in this 400 character limited format.