What could be causing this?

So lately, I’ve been having these out of the blue chest pains that just start up outta nowhere. I could just be doing anything like be up walking around, sitting on the couch, or even lying in bed, and then it hits me. My chest gets really tight, and it gets kinda hard to breathe. It’s been like this a few months, so I just figured it could’ve just been regular heartburn, or caused by my acid reflux but it’s gotten worse. I’ve heard it’s possible that your body “warns” you before a heart attack, but I’m too stubborn to go to a doctor. Last one I went to just prescribed me some acid reflux medication which helped a little. What should I do?
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Instead of responding to each individual comment, I’m going to put this here. Thanks for all y’all’s recommendations, and answers. I’ll definitely be seeing a Doctor soon about this, thanks.
What could be causing this?
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