Hello! If you get time to add information, I may be able to assist you better : )
From what you have described, it sounds like the symptom you are describing is a tremor. This can happen occasionally, constantly or just once or twice and then go away! That's why it's pretty hard to catch it when it's happening to have it evaluated by your doctor. This can mean many things, but because you are healthy otherwise, it may be a little easier to narrow down the causes. Sometimes this is indicative of hypoglycemia... you should especially suspect this if eating helps this problem go away.
This can mean that you have an overactive thyroid (the pulsing and symptoms would be during a thyroid storm in which you have a sudden elevation in your thyroid hormone level). The best way to get this checked out is to have blood tests with a hormone panel done by your doctor.
Sometimes this may also mean that there is a problem going on in the brain or spine. Neurological disorders that can cause this include multiple sclerosis... if you have had a brain injury or if you have something like this running in your family, this can be an early warning sign of something coming on and you will want to get a referral to a neurologist to be evaluated.
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