What treatments will help with dark inner thighs? (Photo)

I've had dark inner thighs since my teenage years due to friction and tight clothing. I went to a dermatologist and got a biopsy. The result came out as epidermal hyperplasia. I used hydroquinone 4% with 0.5% tretinoin for 6 months with 3 month break in between. It made my inner thighs way darker. I also had peeling & inflammation. I'm desperate to lighten my groin area I took azithromycin while pregnant but it was also ineffective. What kind of laser treatment would help? Any other treatment