So, you went to an urgent care which was the smart thing to do as having chest pains is something to first make sure you are not having a cardiac event. At 19, that would be unlikely but not impossible, so glad you were checked out. Panic attacks DO cause what you describe and yes, they do feel like you are dying. They are truly miserable!! But here is the good news . . . panic disorder under the umbrella of anxiety disorder is treatable!! I think you need to go to your regular doctor and explain what is happening. They can refer you to a psychiatrist and/or give you names of psychologists you can begin seeing. I know that sounds a bit daunting but it is the best way to get a handle on this. Know that you will NOT die from a panic attack, it just feels bad. Deep breath, breath in for a count of three, hold, breath out for a count of three, hold, and repeat. This calms you down. Open and close your fists which keeps your circulation going and also clams you in panic moments. I would start a journal to take with you to the doctor in which you job down what happens directly before a panic attack to look for triggers if there are any. Or any sort of pattern. Are you under your parents insurance still?
It's unlikely a panic attack per se, as that wouldn't last 4 days, but it could be a high amount of anxiety. Are you feeling more anxious than usual? Is it possible you tweaked something exercising or reaching for something? Does it go away when you're distracted enough to not be thinking anxious thoughts? And have you followed up with your regular doc for a more thorough check up if you're that concerned? Anxiety can cause a whole lot of symptoms, and it doesn't have to be a full-fledged anxiety attack, and the longer we live under the stress of chronic anxiety the more our bodies start to hurt. Are you seeking treatment for your chronic anxiety, say in therapy?