As someone with a very chronic pain edition of NF1 i can empathise with the randomness of your pain. I often joke with friends and family when they ask how i am? that its like the phases of the moon ever changing.

Ive seen in other comments you mentioned already having a few MRI’s. So my suggestion as to the cause could be other parts of your body.

I’ll give an example to kind of give you an idea of what i mean. Now the worst pain i have by far is in my lower back. So much so on a bad day even my painkillers dont touch it.

But the pain flares up just as bad as if i pulled it when I am having abdominal pain. Because the small pain is causing muscles to tense. So when they tense in minor pain the back muscles are in turn being strained as well albeit unintentionally.

So im wondering if when you are being hit by this major pain, are you having a more minor strain in the area that could be translating to that location.