How would I go about seeking treatment for my hyperpigmentation that won’t go away? (photos)

So first had an incident with hyperpigmentation years ago when I shaved my buttocks and didn’t do it properly with shaving cream, water and not with a nice razor. My entire butt broke out and later scarred and since then I have been struggling to get rid of the dark spots all over my butt. I started using hydroquinone from Amazon and other scrubs creams etc. as well as more natural creams like shea butter. I can tell it has faded slightly but it is still very clear.