My Scottish Terrier Has Been Vomiting On And Off Since

My Scottish terrier has been vomiting on and off since May after she had the Lyme disease shot. Could this be a symptom of the shot. I've had her to the vet several times this summer but they don't know what is wrong. She had no other symptoms and is active as she was before. No matter what I feed her, she still has trouble with vomiting . She is 11 years old.