Dark brown area under my armpits during pregnancy?

When i got pregnant with my son , my armpits were forming a dark brown color and also in between my legs right under my Vagina...doctor told me it was hormones and should clear up soon, but its been almost a year and nothing is different...i cant wear short shorts bc you can see it, and i hate wearing strapless shirts due to the same reason, has this happened to anyone?? any suggestions with what i can do??