Why Does My Teacup Chihuahua Act Like Shes Choking?

My dog dose the same it just mean they don't like the food and are ready to breed

The smaller the dog is ( Chihuahua ) the more compact his/her body is which includes their snout...which makes it harder for them to breathe so a lot of times they snort or gag.... Dichihuahua

There isn't really any such thing as a teacup (or micro or pocket or whatever else was made up for sales purposes) Chihuahua or any breed. There are long coat Chihuahua's and smooth coat Chihuahua's and other than that they are just a Chihuahua no matter or how big or small they may be. If your pup really is very tiny (less than around 4 pounds + or so) they would be prone to a lot more health issues, require more strict care and also tend to have shorter life spans just because of their size.
It may be a reverse sneeze or it may be a collapsing trachea or something. It may help to take a video of an episode on a cell phone or something to show your vet instead of trying to describe it. Here is a link to a video of reverse sneeze and the link to the breed parent club (the people who actually set the standard for the breed ect. For AKC) for more breed specific info. Hope it's nothing. Good Luck.
www.petplace.com
www.chihuahuaclubofamerica.com
www.chihuahuaclubofamerica.com