I find in my own experience that one big pain.... can mask lots of other pains so you don't attend to the lesser ones.

Once the big pain resolves for the most part, the background smaller pains become more obvious.

Double or triple crush is also a factor.

And for some I think autoimmune reactions to nerve peptides released into the circulation, may be a factor too. These broken cell membranes or myelin, may cause autoantibodies to be formed which then go on the attack and cause MORE damage. Not everyone gets this, but those patients with genetic tendencies to autoimmune factors, may have far more PN complexity than others.