I have the same things happen. Sometimes so severe in both arms, i'm unable to drive. Have you been diagnosed with Fibromyalgia? Was it in both arms- I have heard that the heart can also have this effect on the arms. Especially in women. Get checked, please. If nothing else- it'll ease your mind.
Fibromyalgia is diagnosed after other things are ruled out and if you have pain in the proper tender points. You should see a doctor.