I would check out this website:
Hydrocephalus
My yorkie just got diagnosed with this and he was having problems with his legs too. He was all wobbly and had problems walking. My vet put him on an anti-inflammatory and after a few ways it didn't get better. I took him to the neurologist today and he has fluid on the brain. You may just want to check it out... the sooner you diagnose it the better. =) If you have any more questions feel free to message me. I hope your lil baby gets better soon!