While your Maltese may not have fleas, it sounds as though the scratching is allergy related, especially this time of year. It would be best if you can get her to a vet and check it out. Things you can do at home: change her food to no-grain with only one protein. Changes should be made gradually over about a week, adding a little more of the new food each day and reducing the old food until she is eating only the new food. Keep the house as dust-free as possible. Check where she walks outdoors to make sure she isn't too close to allergy-producing plants. Wipe her feet after she's been outside. Your vet will be able to give you more suggestions that will help, The scratching won't stop immediately, it will take a week or 2 if the cause is allergies.