Pressure points are no longer diagnostic. The new information on fibro does not include them any longer.

Hep B has had reports of neuro damage. When it first came out it was linked to MS.

I haven't kept up with it, but you might Google it and see what is new about it. The party line with vaccines is always positive, but some people do develop autoimmune issues when given any vaccine. The autistic community is suspecting vaccines damage mitochrondria in some people with genetic weaknesses for it. Two years seems like a long time unless she had a flu shot this season as well. That too can cause reactions.

It is always possible this is a virus of some sort, and will pass. But if it spreads I would be aggressive about it.
Neuropathies that have an autoimmune component can be treated early and avoid long term damage.

I'd get a Mono spot also. Kids present oddly with that. It is a simple blood test. My son had mono for weeks before it seriously became acute. He had a lot of heart palpitations with it (which I did not when I had my turn decades ago).
I thought that was odd for him.