My babyyy

i have had my dog since i was like 5 and i'm turning 14 on the third of sept. but anyways i think she is going to pass away soon because she can barely sit without her legs shaking because she is also fat. i kind of feel like i'm over exaggerating but i really don't know. i had to lift her off the couch to get her to her crate before i left for school one day and i don't know if i should be scared right now. she is like 10 years old right now... any words of wisdom?