I don't know if this will help, but my boyfriend started suffering from random swellings a couple of years ago.
The first was his tonsils, but he's since had swellings on his lips, tongue, face, back, arms, hands, stomach, legs, knees, feet... sometimes it'll start in one place and move to the other, eg. left side of face to right side.
He's been to allergy specialists and had blood tests, but they can't find a cause, and the only trigger they found was stress.