Brief Answer:
Man in the barrel syndrome.

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

That description of paralysis in both arms without involving the lower limbs or the face corresponds to a syndrome called "man in the barrel" syndrome (as if your body was inside a barrel and couldn't lift your limbs).

There are many possible causes like vascular, infectious, metastasis etc, but given the transitory nature of the episodes the cause is most probably vascular, related to lack of blood supply. Now that lack of blood supply is most probably either in the brain cortex, in the region responsible for arm motor function or in the anterior spine.
If in the brain it is due to low perfusion which can be because of episodes of very low blood pressure, or because of narrowing of carotid neck vessels bilaterally from atherosclerotic plaques. The reason it would involve only the arms area is because it situates in the borderzone between two main arteries supply area. It is most distally located area so it suffers first, before other areas which are more centrally located either in one or the other artery's supply area. I hope I am making sense to you.
In the spinal cord it may be due to lack of blood flow in the spinal arteries, may be either from atherosclerotic plaques of vertebral arteries or due to neck degenerative issues like herniated disc which compress these vertebral arteries.

So, from a practical point of view, to identify the precise site of origin some tests are needed, like imaging of cervical spine preferably by MRI as well as the neck blood vessels, for the narrowing of neck carotid or vertebral arteries. Also a heart evaluation with EKG and ECHO is necessary for heart conditions which might cause low blood pressure episodes.

I remain at your disposal for further questions.

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Brief Answer:
Read below.

Detailed Answer:
Thank you for your feedback. If the manifestation is the same weakness, difficulty lifting upper limbs, my opinion remains the same. There are many other neurological conditions which could produce bilateral arm weakness but it would be persistent, not coming and going as you describe, that usually is associated with blood vessel issues.
A much more benign explanation would be anxiety, but that is left only when the rest is excluded and while it can commonly cause abnormal sensations like numbness, tingling etc in the upper limbs, it isn't that typically manifested with isolated weakness.
So I believe you should see a doctor asap, if really not possible today perhaps take some aspirin, a blood thinner, even if it turns out to be nothing in the end it won't do any harm (if you have no allergy, active stomach ulcer). Try also to stay well hydrated.

I hope to have been of help.

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Brief Answer:
You're welcome

Detailed Answer:
Hopefully nothing serious will turn out.

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