I Have A Pain In My Upper Left Back Under

I have a pain in my upper left back under my shulder blade. I cause severe pain down my left arm from under the upper arm down to my finger. My fingers have been cramping and my arm pain ins like a 1" line the I can not touch and runs the lengeth of my arm. It has caused severe pain that twice I started sweatng and felt as if I was going to passout or vomit. I have not it passes after 20mins of sweating and feeling like I am going to pass out. My legs are very weak. I took my blood pressure and it gets an error reading in my left arm where the pain is and 118/84 in my left arm with a pulse of 82. I am pale and weak. any ideas of whats up?