Brown, metallic discharge when wiping accompanied with vaginal sensitivity/soreness on outer upper labia. ?

Sounds like vaginal : Dryness,which could be caused by infection,aging,,certain skin diseases involving the vaginal tissue.

Needs testing: A brown discharge is likely old blood. Since you also have an area of vaginal soreness and sensitivity then testing is warranted. See an Obgyn for a pelvic exam and testing to determine the cause and treatment.