What kind of tightness ? Like pressure?
if the pressure/tightness is in the CENTER of your chest, it is more than likely ANXIETY. If you are having tingling/numbness in your left arm and or pain, then go to the Hospital.
Anxiety can cause chest pain. I recently withdrew from a drug, and the withdrawal side effect is rapid heart rate, sweating, and anxiety. My heart rate was at 114-120bpm for a few days, was AWFUL. My chest hurt SO bad. I almost worried about it, but knew it was from the STRESS.
I read that if it's in the center of your chest, it is almost 100% anxiety/stress related. In my case, my body was going through havoc. This passed for me. It will pass for you once you find the root cause. Anxiety stinks, but it won't kill you. :)
Keep in touch!!