Black spots on the legs that do not improve with treatment can be due to pigmentation caused by irritation, allergy, or ongoing skin inflammation. Keep the skin moisturised, avoid scratching, protect it from sun exposure, and use gentle skincare to prevent further darkening. Wear loose clothing, maintain hygiene, and avoid using strong creams without guidance. Since it is not improving with the current treatment, consult a doctor to review the cause and guide a more suitable therapy.