Please Help. My dog will not stop shaking and its not just bcause she is cold!!!

[Jkers866]

I have a 2 yr old female shih tzu. She started shaking really bad about three weeks ago so I took her to the vet and her blood work and physical came out fine except that she had a really high fever. He thought that she may of had a bladder infection so they put her on an antibiotic. Well she has been on it for two weeks and the shaking has not really stopped. Sometimes its worse than others. Sometimes not at all. She still acts perfectly normal (besides the shaking obviously). She eats and drinks goes to the bathroom and still loves to play around with my cat. I dont want to take her to the vet again. The last bill was $150 and it didnt help out any. It would be nice if I could come up with a reason for this and then just take her back there and tell them what I think it is. Here is a list of things that are kind of out of the ordinary that she does or operations she has had:
Spayed
She had a lump on her side removed
Ear infection
She eats cat food more than she eats her dog food
She eats quite a bit of people food too
Sometimes she will throw up but its just a clearish foamy kind of liquid
She has had two or three "episodes" where she stumbles around like she is drunk/or having a seizure. this last about 20 secs.. then she would start shaking..but then she is fine going about her playing...she loves to play.

PLEASE HELP ME!!!!