I have a lot of pain on my left side of the body?

Hi, I am suffering with pain on my left side of the body. starting with my shoulder arm and forarm and the chest on the left side. then the back lower rib then suddenly the rite side of the rib and the right side arm and the whole hand. Then the pain shifts back to the left side on the lower chest and then the middle. the pain feels like a muscle pain when one works in a gym then the shoulders also pain. I have been twice to a doc thinking it was a cardiac attack but they ruled it out saying its a gastric effect. i have done a ECG twice and twice i was told i have gastric problem thats why i have these pains. My Bp is 150/100, oxigen intake is 98 % and suger is 161 post fasting.. Please let me know wht am i going through.. it would be helpful