Why Is My Two Year Old Chihuaha Having Weakness And Discoordination?

Last night my two year old chihauha was having trouble getting up and walking. He was totally discoordinated, tripped down the stairs cannot walk. I took him to the emergency animal hospital. This morning they told me that he is still the same. His blood tests came back normal. They ruled out lymes disease and are now going to test him for meningitis. He is only Two PLEASE HELP me!