Since she is already taking Doxycycline your vet does not really have to test for tick borne diseases, such as Lyme, Ehrlichia, Rocky Mountain Spotted Fever
, and Anaplasmosis.
Tramadol, the pain medication, can also be used with Prednisone, and may help you lower the prednisone dose. Try to keep her weight down by reducing her food intake, and by giving her carrots, celery, and other non-starchy vegetables. I know this is difficult because Prednisone causes a voracious appetite.