I have a two-year old cocker spaniel who has been sick off and on for the past week. She has mucus-filled, liquidy stools and periodically vomits a bright yellow foamy substance. She still is eating and drinking normally and has energy. However, I am concerned. I have given her peptobismol and have made sure that she eats no table scraps--just her Nutro dog food with some turkey each night. Should I start her on a 12 to 24 hour fast or should I bring her to the vet immediately?