Tightness in my chest... should I be worried?

Sounds like a panic attack, and they suck and they often are described the same as the people that have real heart attacks. If you are 18 then your heart is probably fine but even if you know 100% that its just a panic attack they dont just go away and i would recommend going to a doctor let them know whats going on and they can give you something that helps the pain/palpitations/sickness, i hate the doctor and i hate taking pills but panic attacks are one thing i refuse to deal with on my own.