Hi, the condition strongly suggests angioedema which is due to hypersensitivity reaction (type 1). We cannot rule out the allergen, we can just guide to rule out the probable allergen. Drugs like amoxicillin, certain painkillers, certain garments, environmental allergen and certain food (fish, mushroom, peanuts, soy etc) can cause such reaction.
You need to keep track of things (maintain a diary) you were exposed to such as food, cloths, drugs etc. and you should avoid further exposure. If associated with pain and redness then there might be secondary infection and needs proper antibiotics to prevent further spread and complications.
If you have breathing problems, it can be due to associated laryngeal edema then needs immediate attention from a doctor. Drugs like Adrenaline, anti-histaminics and corticosteroids are the standard mode of treatment which should be taken after consultation from physician. Take care and regards.
Could be from really severe allergies