Levaquin (levofloxacin) is in a group of antibiotics called fluoroquinolones which are typically used for bacterial infections that don't respond to other types of antibiotics.
Two fluroquinolones more freuqently used in dogs are Enrofloxacin and Ciprofloxacin which are in the same 'family' as this medication is.
I would suggest asking your vet for side effects to watch out for and when to stop the med if your dog shows any of them.
You might want to do a biopsy of the area and sensitivity testing to find out what the underlying issue is (fungal, bacterial, a tumor) before deciding on a treatment plan. Sensitivity testing would tell you what medication an infection would best respond to instead of just trying one.
Hope this helps you!