First off welcome to YT.
I'm so glad you could join the group. Now for my opinion on your question. She needs to be with you. If she is swelling, this is not good at all and can cut off her air supply. I would say it's the shot. My Chihuahua who passed away this past Sept. at 16 years old, did the exact same thing when we got her first shots at 4 months old. She never got another shot the rest of her life. Make sure the Vet. has it written in her record to give her the benadril BEFORE giving any shots, and to also break all those shots down onto smaller groups. Next, no annual shots. Wait at least three years before getting any more.