My name is***** and I am sorry to hear that Piper is sick. First, how old is Piper? Has she had all of her vaccines? Have you taken her temperature? Does she have a fever? Also, How much does she weigh, so I can make some recommendations for medications.
Dogs, especially young ones, can vomit for many reasons, but the most common one is dietary indiscretion (eating something she shouldn't). The offending item could already be gone from her intestines but the irritation remains. She could have also eaten something that has blocked her intestines and now she is obstructed. Other causes of vomiting and diarrhea in young dogs includes infection with a virus like Parvo or intestinal parasites.
For tonight, I would recommend the following things-
1) Pepcid (famotidine) give 0.5mg per pound of dog, rounded up to the nearest 1/4 tablet size. You may need to force the pill down her throat.
2) Tums- 500mg or one tablet.
3) Offer only small amounts (1/2 cup) of water once every 30 minutes
4) withhold all food tonight
5) In the morning, try food again, like boiled chicken and rice
If there is no more vomiting tonight, she can wait until the morning to see your regular veterinarian. They will likely recommend blood work, x-rays, a fecal and possibly a parvo test.
If she continues to vomit tonight or if she has a fever, I would strongly consider taking her to your local animal emergency room this evening.
I hope this answer helps you. Feel free to contact me if you have any further questions.
Kansas State University
College of Veterinary Medicine Class of 2001