What Causes Pain In Left Side Of Chest And Arm Along With Pain Under Breast?

I have been having severe left sided chest pain and under left breast for 3 days now, some left arm pain and numbness in fingers, it hurts to cough ,I have to sit up to do that, I cant sleep on left side cause it hurts too much and I feel like I cant breathe, I haven t gone to er cause im not sure if its heart related or just gas, I do know its a consist pain, for me to take a deep breathe even hurts. Can you help me?