This is a tough one. I have freaked out about this once. After 2 days of not keeping anything down I rushed Samson to the hospital. 24 hours in the emergency vet, lots of tests and $1000 later there was no answer. Could not find a single thing wrong with him. Sent him home with instructions of a bland diet, boiled boneless skinless chicken breast, white rice and cottage cheese. He was fine after that. Samson lives a sheltered life. He is an inside dog by choice, he wants to be where we are. My house is puppy proof and I can pretty much be sure if he's puking it's probably just because he isn't feeling well, not because he ate anything crazy. So what I do is start with Pedialyte. He doesn't really like to drink it on his own. I have to give it to him with a medicine dropper. It's not a struggle like I'm forcing it down his throat, but unless I do that he won't just drink it. They get so dehydrated from throwing up and if I allow him to he will drink a bunch of water, makes him too full, pukes again, nasty cycle you know? So I actually pick up the water bowl and just give him pedialyte for like the first day. Same with food, she is probably really hungry but unless it's a small amount of food she will probably get too full and throw it up. Imagine the times you've had the flu and have thrown up for days. Doesn't take much to make you full after that right? So I start with like 1/4 cup of food. Wait for a while to make sure she keeps it down. Feed in small amounts. The boiled chicken/rice idea is perfect. So thats what I do, pedialyte, limit food and water. So if you are sure she hasn't eaten anything crazy (like rat poison versus just like some paper) or something I would give it a little time. This happens to Samson maybe a couple times a year, last time was 4th of July weekend. He was sick for like 2 days but with my routine above he healed up just fine.