How do I treat this unusual light patch thats appeared recently on under eye dark circle? (photos)

I had fillers done under my eyes 2 years ago bcos they were extremely hollow, dark & noticeable. I developed this small light patch under my left eye ON the dark circle area; i dont know if its due to the filler that i had or if its some type of pigmentation problem or like vitiligo maybe? I've still got some filler left under my eyes btw. Could anyone try & help me identify what it is so I know what type of treatment i'd need to get rid or what type of specialist to see for this please.

No doctor answers yet