if it is in both arms, (or even not--or it goes from one to the other) and it 'randomly comes and goes', it may be triggered by something physical, such as a food, and might in fact end up causing a tendancy to liver congestion, say, but my intuition says it is "psychological", and that it is "inherited".(edit--which is not to imply it is any the less real, in terms of what manifests for you--far from it. At the same time, it may be that it can almost instantly be resolved.) I would look into The Emotion Code, and see if it resonates with you. You can even get the book for free,
and do the clearing yourself. You have nothing to lose.
(i'm not affiliated with the Emotion Code, but I've used it, and found it good.
Interesting thing about the liver, since it stores a lot of emotion, (esp. anger and rage), doing Liver Flushes can release a lot of emotion. I've done about 5-6 liver flushes, maybe more, I forget now. But I certainly have experienced stored emotion leaving me, literally, physically as the stones moved out, and flashes of memory appeared along with them--and I've experienced the flush leaving joy and peace in its wake. I've only come across the Emotion Code recently, and my sense is, it is profound and important., as a process.