My dog has a rash and it isn't bothering her but i want to get rid of it.....?

she is an american pit bull terrior and she has this weird rash on her neck and tail..there is some hair loss but it doesnt look like mange...its dry and not the same color as the rest of her skin..it doesnt seem to itch her at all either...i dont want to waste money at the vet if its treatable at home but if its not i need to know so i can bring her to the vet..if you know anything about this please let me know thanks