Does my dog have depression ?

When i touch him he cries. He is 5 years old chiuahua mix terrier
Started yesterday night. But yesterday he did nothing but lay on my bed with several of his toys n sleep. My dog is most attached to my sister so when she comes home from work the dog is extra happy but sometimes when my sister ignores it (yesterday) the next day he starts acting like this.
when u say come baby ( his name)
he wags his tail but squats to the floor and slowly moves with his head down
i have a feeling nothing is wrong with it its just acting up but his crying breaks my heart

You just asked this 5 minutes ago. There could be 100 different things wrong with your dog, it could be depression, it could be any number of things wrong. Only your vet is going to be able to tell you what is wrong. Sorry.