My basset hound keeps jerking all the time and falling over. She is also drinking a lot of water? What could be wrong with her?

It could be a number of things with the thirst suggesting diabetes. Only your local vet can really diagnose the problem and treat it. The jerking could mean a problem needing prompt attention.

Florence, pardon me, but how can you sit there and watch that happening to your dog? Call your vet NOW. Please. Get him in to the vet today. It is obvious there is something wrong and he needs medical attention. Please give it to him.