It is very hard from the photos to discern what is going on, but it appears as if you have what is called "post inflammatory hyperpigmentation." This is pigment that develops after a trauma or irritation, likely due to your previous history of bites or cuts on your legs. You will need to see a cosmetic dermatologist who has training in lasers. You will likely need a combination of topical treatments with bleaching, vitamin A and C, and sunscreen. There are options such as microdermabrasion (silkpeel), chemical peels, or lasers that may be useful. But sometimes no treatments are affective for this, and you need a formal evaluation to determine what may or may not be helpful. I wish you the best of luck, Dr. Emer.