My name is***** and I think I can give you some help with Kelly. While I don't recommend feeding chicken skin to your pets, the amount Kelly ate 4 days ago is not likely to be today's problem. Dog's can vomit for numerous reasons, including eating something they shouldn't (human food, trash, toys, rocks, etc), pancreatitis, intestinal blockage, inflammatory bowel disease, liver or kidney problems, and many more. The good news is that dogs often will have something that irritates their stomach, they will vomit one to two times, and then recover without any problems. This is about 75% of the cases that I see. What I recommend is if your dog vomits one time, pull up the water bowl and wait 4 hours before offering it again. If she vomits 2 or 3 times, again pull up the water and watch her very closely for more vomiting, check the gum color (should be a nice, moist medium pink), and press on the belly to see if it is painful. If she vomits more than 4 times, has pale gums or her belly is painful, then I recommend taking her to your regular veterinarian for further evaluation. They may recommend blood work, abdominal x-rays and medication/shots to control the vomiting. Also if your pet refuses food for more than 24 hours, I would also consider taking her to your regular veterinarian. There are no good over-the-counter medications that can help with vomiting in dogs.
I hope this answer helps you and I hope Kelly feels better soon!
Amanda Mouradian, DVM
Kansas State University, College of Veterinary Medicine Class of 2001