Hi I Had A Sudden Pain In My Left Side

Hi I had a sudden pain in my left side of my chest right under the inner boob area, it wasn't sharp like a stable, but like a hard presure like I sudden hit with a hammer, I quickly felt hot and suffocated and sat up straight, I had been leaning over to my left side watching TV. The pain immediately went away, and it just hit me that once, no following pain, my muscles in my back are tense, but I cut hair for a living so it is normal to be tense. I have had these spells before, but they are always months apart, what could cause this.