could be an ear infection.
baily had mites when his ears smelled but he was scratching and shaking his head too.
does she have a lot of ear hair? i had to get bailys ear hair plugged to be able to clean the ears better. i put some drops of a mild cleaning solution (specially for dog ears) in his ears every couple of days and he never had problems with his ears again.
if she does have an infection or mites you will have to let the vet have a look at it though. i'd keep watching her for now and see if the smell gets stronger or if she starts scratching or shaking her head. if not normal ear cleaning drops might solve the problem.....
(when using ear drops make sure that you massage the ear from the base to the top not the other way around or you could hurt the eardrum)