What Causes Swelling, Dryness On Lips?

for last two years, have had reoccurences of lips swelling, usually waking up in morning and finding them swollen,sometimes blood on the pillow. very painful and then after a day or so, begin to go down, then start cracking and peeling. have had several allergy tests and doctors can find nothing wrong. only mild allergy to eggs and peanuts. any ideas?