Brief Answer:
Possible BFS (benign fasciculation syndrome).

Detailed Answer:
I read your question carefully and I understand your concern.

From your description you have what are called fasciculations, brief spontaneous contraction of a small group of muscle fibers. They are not specific, meaning they can be found in many conditions. Most commonly they are part of what is called benign fasciculation syndrome, a syndrome without a well defined cause (anxiety is a hypothesis), which as the name indicates is benign and doesn't carry any threat. In the absence of other symptoms and judging by their widespread nature that might well be your case.

However before reaching to that conclusion some other possible causes should be excluded. For that reason a neurological physical exam is necessary to check for other symptoms such as weakness and muscle atrophy, abnormal reflexes etc which might indicate some neurological condition. When in doubt an exam called EMG (electromyography) which studies the electrical activity of the muscles may be done.
Also since they can be in the setting of hormonal and metabolic disorders some routine blood tests are done such as thyroid function, electrolyte panel (including magnesium level), blood sugar, liver and kidney function, blood count, erythrocyte sedimentation rate.
These steps are not necessarily on an emergency basis as even if something is found it is not immediately life threatening, but are recommended to assure the fasciculations are benign.
On a last note, people searching on the internet are often worried and ask me about a condition called ALS (amyotrophic lateral sclerosis), but before you ask as well I would like to say your description doesn't make that diagnosis likely, fasciculations are not so widespread so quickly and there are other signs on neurological exam.

I remain at your disposal for other questions.

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Brief Answer:
Read below

Detailed Answer:
Hello again. No I did not receive any reply yesterday only in this last hour.

Regarding your question it is difficult to give a precise answer as it varies from an individual to another. If a cause which can be corrected is found such as low magnesium or thyroid dysfunction their treatment can make it go away.
In those cases where all tests turn out normal it may be related to factors such as stress and anxiety, meaning you may have periods where you may be free of symptoms with intervals during which the symptoms may manifest again, so you can expect improvement, even disappearance, but that doesn't guarantee they might not reappear from time to time.

I hope to have been of help.

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