This sort of thing can be caused by an auto-immune disorder or a severe allergic reaction. These novel vaccines based on viral fragments certainly could cause either.
They are watching what happens after the poke. But, do they care that their shot is causing pain and death?
The people who thought this shot up are sociopaths, with needles.
I’ve understood the J&J to be a traditional type of vaccine; not the m-RNA type (?)
JnJ is not a MRna vaccine it is a classic weakened virus vaccine. In this case an androvirus with the Rona spike protein sequences added to its shell to mimic the real Rona. This kind of reaction can be had with any live or weakened virus vaccines you can have the same thing happen with the quad dose flu vaccine or measles or polio it is rare but it does happen with those other vaccines. The JnJ and the Novavax both are classic whole virus vaccines.
A family member had a severe reaction to an IV antibiotic given for pneumonia a few years ago. The intestinal lining o sloughed off resulting in bleeding and a week in the hospital.