What you are experiencing is discolouration that occurs after bites with post inflammatory change causing hyperpigmentation, which is also known as post-inflammatory hyperpigmentation – PIH. This is a common occurrence after your skin recovers from an injury such as bites. Depending on the underlying cause, the pigment may be deposited in different layers of skin, either the epidermis (superficial layer) or dermis (deeper layer). Treatment options include topical treatments with medications containing hydroquinone, retinoid or steroids, and lasers which include Q-switched or dual yellow light. However, all of these treatments will need time to take effect and a combination of treatments is recommended.