I Have A Pain On My Left Side Chest Sometimes

I have a pain on my left side chest sometimes on the middle of my chest, and it's been almost 2 weeks now.
I feel as if my heart is beating fast and it's so loud. When I take deep breaths, I have this striking disturbing pain on my "heart" as if the air that I've breathe in goes straight to my heart and as if I have a hole in it and becomes so painful.
I struggle to sleep at night. And when I lie on bed, my left side and middle part of chest becomes so painful and I struggle to breathe. Even when I sleep with my right hand sides still, it beomes better when I lie with my left hand side or with my stomach.
At times I feel hot flushes on my face and back. And I often feel dizzy and nausea.
And now I've just notice that when I hear ambulance or police siren even when my phone just rings or makes that message alert tone my heart start to race even faster and painfully.
Please help me, what could this be?