Chest Pain Problems Exercising

For the last few months I've had pain on left side of my chest as well as armpit. Leaning forward in any direction makes it feel worse. Easy everyday things such as climbing a set of stairs or doing a lap in the pool make me feel dizzy and have an uncomfortable feeling of tightness in my chest area (not out of breath). Worse when lying down at night on back feels like my chest is being pressed on from the inside. Putting a heating pad on it helps some. Lastly, sometimes right before I fall asleep my body goes numb from the neck down for 5 to 10 seconds and and I'm unable to physically move. It almost feels like my heart stops. Afterwords I'm able to get up and can feel my heart rate increase rapidly. Usually after this event occurs the chest pain decreases and I fall asleep after. I am 20 years old.