I believe my dog is seriously ill, can someone help me?

I have a female Japanese Chin, she weighs about 9-10 lbs and is 6 years old in a few days. She isn't fixed, and hasn't had any litters. About 1-2 years ago, she was exhibiting odd symptoms: drooling, facial drooping, clumsy walking, laying and sitting down a lot. It happened twice, each time I notified a vet but nothing was ever concluded. It hadn't happened since until now within the last month. She's been difficult to walk because she almost seems resistant to walk, her character has changed and I end up having to tug her along the way just to get her to do anything. During those times she isn't exhibiting any odd symptoms other than what I mentioned. But other times she starts to show the same symptoms she showed a few years ago. She's drooling heavily, clumsy walking or it seems like her legs just lose strength and she cannot walk properly, and she starts to lay down and sit a lot. It appears whatever condition she has is worse now and I do not know what to do. I plan on going to a vet tomorrow to take her in, there's an emergency animal hospital across the street thankfully. My question is, does anyone know what this might be? What can I do to help her until I take her to the vet? Is there anything I can do? I'm very worried about her, she's my first and only dog I've ever had. I consider her my family. I hope I provided enough details, if anymore is needed I'm willing to answer.