DOG SICK 7 MONTH- cause is unknown after several tests

[Gemelas]

I have a female 6 years old chihuahua. She had been for seven months with several problems. She started with tremors,
continuos fever-105 f, rapid breathing, lethargic, weakness and large quantities of urination. Provided an antiobitic she got only a little better for a few weeks.
Again fever cameback. Very evident she was in pain, crying,
tail between legs. She was grabbing her head with both paws
showing pain, also rub her head against objects and cry.
Listlessness, spaced out, trouble getting up, NASAL DISCHARGE,
nose twitching, a lot of scratching and licking herself.

Test performed on her: MRI of brain-OK
blood work- OK
ultrasound stomach-OK
serology- OK
Fluid tap-ABNORMAL

The fluid tap showed ahigh count ofwhite cells indicating
possible BACTERIA, VIRUS , ETC.
After this SEROLOGY test did not show the cause of her encephalitis.

Antibiotics such as BAYTRIL, CLAVAMOX AND PREDNISONE
only aggravated my pet's condition. Her tremors and pain
and difficulties moving had increased.

Doctors told there is nothing else they can do. They do not
know cause of her high count of blood cells. Is there any other tests?

I am afraid her immune system is too weak to continue Prednisone. Is there a homeopathic medication
that could help her encephalitis?
Please help me save the life of my little baby.