My 4 year old Yorkie terrier has a hot dry nose and is struggling badly to get up the stares and can barely even walk but its only in the back legs and if you touch them his legs shake slightly but does not yelpi don`t know what to do please help ASAP

Sounds like a fever, maybe from an infection. Take him to the vet for a diagnosis which may include a blood draw

I agree with Ballengerb. This needs to be seen to by a vet. We can guess what's going on, but guesses aren't always accurate, and won't help your dog.

I'll make it three to none for seeing the vet. It sounds like a nerve problem of the lower back.You say there doesn't seem to be any pain... not something expected with a disk problem, but it may be an infection, or even a tick bite affecting the spinal nerves.

There's a couple good reasons to see the vet, and let's hope they aren't really accurate diagnoses, but actually something simpler.