Vital Medical treatment needed for Snowmane

This past week Snowmane has trouble walking, his back legs have been sluggish and he has had problems walking, meaning he cannot jump up on to things anymore and he has real trouble going up and downstairs.

I have been to the vets numerous times over the last week checking all sorts of things including Urine and Blood all of which have come back fine. 

After showing the vet a video of him trying to walk up the stairs she concluded that it is probably a neurological problem but since his front legs are completely fine it is probably in his lower spine and more likely his hip as it affects one leg more than the other.

I'm raising funds in order to pay for the MRI scan need to identify the problem so it can be fixed and return Snowmane back to his usual boisterous self.

Snowmane has meant everything to me since he showed up at my house having lived rough, and my house would be empty without him.

Any help would be so gratefully received and should I make my target and if there is any money left over It will be donated to the Cats Protection to help further homeless cats.

Thank you for any help you can give.