Every so often, every 2-3 months, I get this exact same thing. It's so painful I cannot write my name or circle something with a pen. I'm a cashier and for a minute or so cannot press the right number. I try to wait it out. So far it eventually passes.
This is not normal and as you are concerned, you should make an appointment to see your doctor and get the appropriate checks done to rule out heart problems.
You do not say whether you do any physical work outs. These may be the cause of muscle spasms in your upper arms.
Let us know how you get on.