actually your body can produce excess white blood cells (sign of infection) for any type of inflammation
this is going to sound kind of stupid but have you tried a mega high dose of an antihistamine when it happens?
you kind of sound like me right before I break out in huge inflamed hives ...for which cause was never known
for me it always starts on my elbows and knees...the joints get swollen before the rest of me breaks out
about a million other things come to mind though...pseudo-gout, raynauds, some sort of vascular disorder causing a break down in capillary walls..spilling plasma everywhere...actual physio-mechanical problems
I start with a double dose of one of the new generation antihistamines though and see how the swelling responds