Chest and arm pain while breathing?

Every now and again, lets just say once a month. I have chest pain, under my breast and ribcage. It always radiates to my left arm and often leaves a residual ache there for a little while. But it does not in my chest. It is very brief, probably less than a 45seconds. If I try to breathe while it is occurring, the pain will multiply to about a 9 out of 10 scale. So, i try to hold my breath till it passes. Since the pain doesn't stay in my chest, should I worry. From what I've read, I don't believe that it is a heart attack. Maybe indigestion....I'm flat broke and wont be going to a doctor unless it's a hospital so I can make payments. Is this what indigestion, or even gas, feels like?