I suggest you to go on a professional vets cause you cat seem really old and this cat really has a problem just like i seen a a veterinarian in Finland at http://www.jar-vet.fi/ where i seen a same problem which cause of being old of the pet.
I am also wondering about it in some place i seen a black cat but they are just aspin ,In Finland in a veterinarian at http://www.jar-vet.fi/ i also seen a black cat however i did not ask what is the breed of that cat cause my dog is really sick that moment.