About a week ago I had these two terrible people drop off a purebred Maine Coon cat at my house that they just didn't want anymore. She is 12 yrs. old and absolutely beautiful. She seems to be in good health but when she walks or lays down she shakes sometimes - kinda like she is cold?? Is this because she is old or a BIG cat or should I take her to the vet?? I foster for a rescue and usually don't take my rescues to the vet for an initial check-up only if I think something is wrong. Any advice would be great....