Thanks for contacting with your health concern
1. without being able to examine you directly, I'm of the following opinion:
i. In relation to hyperpigmentation
, the causes can vary from skin pigmentation issues to Lichen planus
pigmentosus" or "Cautaenous amyloidosis" so it is best to have a direct physical examination with a Dermatologist
for proper diagnosis and relevant investigations [dermascopy or skin biopsy] for further management of your condition
PS. As you have tried a lot of products in the past with unsatisfactorily results thus consultation with a dermatologist is necessary, till then use a broad spectrum sunscreen and certain safer creams containing kojic acid
2. make sure you stay out of sun during peak hours 11 am to 4 pm, or if this is not possible use/apply a good sunscreen with minimum SPF of 30
3. Exfoliation of skin done regularly takes off dead skin cell replacing with new one.
4. applying lemon juice at night and washing the next morning helps in skin lightening.