What is wrong with my dog?!?!?!?!?!?

She is a famale mini doxin and about a year old and in her neck area she is losing fur...a lot of fur you can see her skin. She is a shothaired dog and her collar isnt tight around her neck and where her collar normally is is where she is losing fur.Is it because of her collar or something else??Help I don't know why she is losing fur.