Ill do a quick summation of GBS.
Our nerves are coated in myelin, and with GBS our own bodies attack the myelin sheaths around our nerves, they do not damage the nerves themselves, they damage the outer coating. When this happens you can have numbness/tingling/burning/loss of sensation. You also can lose strength in the affected nerves. This usually happens in the hands, and the feet and progresses towards the trunk and is USUALLY rapid in onset. This is also temporary, however with a higher risk of recurrence later in life. Worst case scenario affects respiration.
This is completely temporary, and those with GBS normally experience a full recovery. Think of it as a flu with the nerves.
Variables: Is it one arm? Seems he thought this was a neck stinger, meaning he may not have symptoms in his feet (which is common with GBS). Signs point to potentially being a mild case.
Is he getting symptoms in both arms? If just one arm, this could be a very MINOR case of GBS, that lasts for a month, or two which follows with remyelination of nerves at 1mm a day, etc.
I have worked with and treated those with GBS. Most make a near full recovery, and that is not including the fact Frederick is a high conditioned athlete.
I do not see this as a long term issue, however prayers go out temporarily as GBS is not a pleasant experience. Also, this could be a minor case as well, and early detection can help prevent symptoms from worsening.
GBS is HIGHLY variable. However he will recover to full strength. If you have questions, quote me and ill respond when I can. Gym time now.