Hello.. From past few weeks I have been developing a non tender swelling on my for head on the left side of face above the eyebrow. The swelling appears and then disappears in few hours.. Also the swelling appears anytime.. There's no trail to it. Earlier it felt like I might be bitten by an insect or maybe some allergy... But the swelling is appearing on odd periods... Like just got into bed and suddenly I start feeling a swelling and the next morning it's gone.Kindly suggest why is this hpng