The swelling in allergic conditions is mediated by histamine.

The swelling in HAE is mediated by too much bradykinin.

Since the causes are very different antihistamines do not work much for HAE.

Your description "a mind of its own" is more like HAE IMO.
In HAE bradykinin cannot be metabolized away properly and builds up. When a trigger presents it dumps into the system causing swelling.

There is a swelling potential also with Crohn's disease. This is gastrointestinal inflammation. Mostly this can be with the feet,
but any site can be affected.

PN can be primary or secondary. Secondary is caused by something else. Certain when things swell up the nerves get pressed on and signal that. Fix the secondary cause, and the nerve pain goes away.

Keeping a daily journal of what you eat and what your discomforts are may help you pinpoint what is doing what.