Random chest, arm and back pain. Reason?

I am having pain all over around my chest, arms and upper back for past few weeks. The pain majorly resides in left side of the chest and arms but this pain goes away in moments and comes back later either on the same day or another day. Some days the pain stretches to my neck, jaw and even head And some days the pain feels more like pinching around the chest for a few moments and then it gets all well. I am not sure whether this pain is related to muscles, bones, lungs or heart. Please help me clarify and cure this problem. Sudden pain makes me stop my regular activity and brings slight anxiety which makes things works Also, for reference, I have no existing condition except rheumatoid arthritis. Can that be the reason? Also for the past few days I'm having chest pain majorly even when I lie down straight on my back Please suggest