Suggest Treatment For Black Marks On Neck And Face

Hello doctor, I am 24 yrs old female, I got sideeffect from Tetracyline drugs ( Erythema) 5yrs back. It left big circled black marks on my neck & face, As my doctor told me it wil fade after some weeks but i dont find any changes on my marks. So i consulted other skin specialist doctor and took laser treatment but my mark goes darker. So as suggested by a friend i started using mederma but still i dont find any improvement please suggest.