Weird patch of discoloured skin near boob

Not sure when but I know it was ages ago probably nearly a year ago I noticed a little patch of darker skin near my boob which was also dry. Didn’t think much of it however it has now grew and sort of formed 2 new smaller patches???

They are quite dry and sort of rub off like dead skin whilst in the bath/shower. However appear again the next day

Does any1 know what this is or what it could be?