Weird discolored circle on body, help?

Lexi • 19 years old/ Insta: lexihedlof

Does anyone know what this is? It started out the size of a pea n now this size n has stopped growing (I think).. it doesn't hurt or itch or burn.. but it appeared in the summer of 2015 or 2016 I believe, I don't remember fully lol..

Any ideas??? Thanks!