hello. i have a dark redish patch in the back of the knee, they said it s fixed drug erruption. it s not itchy, i think it s here since almost 2 years, on both knees. i don t take any drugs, only paracetamol, ibuprofen from time to time. sometimes i used antibiotics when i was sick with flu but that s it. i have 28 yrs. how do i get rid of these? thanks!!!