Hello, I can understand your concern for swelling and change in color of scar after using Melalite. I can get from your history that you have the best possibility of Irritant/ Contact dermatitis or in simple words allergy to contact contents of the melalite cream. To explain you elaborately about the possible condition - Due to exposure to hydroquinone in melalite you got immediate reaction to it. So there can be initial redness and itching with mild pain sensation. As we scratch it or due to exposure to environmental factors such as sunlight, sweating dust and hot humid climate, it can get aggravated. I suggest you to immediately stop the cream and do not use further without a dermatological guidance. For the interim of relief do cold compression and apply a calamine lotion. You can take further guidance form a dermatologist for best help. All the best.