Last night, i had sudden chest pain/tightness and left arm pain. it went away, but today i had chest pain again. what do i do?

Go to ER IMMEDIATELY: You may be young, but that does not preclude a heart attack.The symptoms you describe, esp. if they are associated with excessive sweating &/or nausea are typical signs of heart attack & angina in males.Go to the ER NOW & get it checked out.If they find nothing abnormal, they may require a cardiac stress test. If nothing cardiac is found, further exam should be undertaken by you family dr.