Dear 22 year old person - you don't mention your sex, past history, occupation or family history. I assume that bruising on the legs is spontaneous and not related to trauma. Your other symptoms include fatigue, chest tightness and palpitations. At your age bruising of the legs is unusual and if it occurs without trauma it definitely calls for evaluation including a complete red and white blood cell study and perhaps study of some clotting factors.
The chest symptoms at your age call for ruling out pericarditis (an inflammation of the sac around the heart) and other heart-related problems. There is the outside possibility that the chest symptoms correlate with the leg bruises.
You should consult a physician concerning these symptoms. Please do keep in mind that I am unable to diagnose medical conditions online.