Here's what's going on with your dog.....
I am 99% certain that this is the result of excess stomach acids and bile. Most often you see this when the dog has an empty stomach - first thing in the morning or shortly before a scheduled meal. All of the gastric acids and bile can upset the stomach lining when there's no food present, resulting in vomiting.
To fix this problem, you'll want to feed your dog more often. If you feed him once a day, split the food in half and serve it in two meals instead of one. If you're feeding him twice a day, split those meals and feed three times a day.
In other cases, some dogs will also have problems associated with producing excess gastric fluids, so no matter how often you feed them, there's still excess fluids present, resulting in the vomiting you're seeing. You can treat this with a medicine such as Pepcid AC. The dosage is .25 to .5 milligrams per one pound of body weight, given every twelve hours. You'll want to start out at the lower end of the dosing range and really, this is only needed if feeding more frequently doesn't do the trick.
Also, you have to remember that when the fluids and bile are sitting in an empty stomach, they cause the stomach lining to become inflamed and irritated. This is what triggers the vomiting. But once the stomach is upset, it can take time for it to settle. So in many dogs with this problem, you see chronic stomach problems like vomiting after meals too. Usually, treating the problem with the excess stomach acids and bile will solve the problem entirely. You can sometimes end up with a circular problem: the dog is vomiting because the bile has upset the stomach, and the stomach is empty because the dog is vomiting. And then the dog won't eat because of the stomach discomfort, but eating is the one thing that will help fix the problem. So anything you can do to get her to eat should help.
I also have a few other measures you can try for sensitive or upset stomachs:
Firstly, when you visit the vet next, discuss the possibility of switching your dog to a prescription bland diet that is especially easy to digest. I use Hill's I/D food with my dog, but I know there's other brands and they can make a huge difference in reducing upset.
Next, feed wet food or hydrated dry food. To hydrate dry food, add hot water, let it sit and the kibble will swell. This way the kibble isn't swelling in his stomach, which causes upset, especially if he ate til he was full - this makes him beyond full which is never good.
Try feeding from a raised food bowl. This can reduce the amount of air he inhales. Until you get one, you can feed on the stairs. This is actually ideal, because gravity works in your favor and the entire body is sloping downwards.
Don't let him eat around other pets or other stressors. Feed in a quiet, out of the way area. We don't want him eating his food too quickly, as he'll end up with extra air in his system.
Don't let him drink large amounts of water after eating. Just a sip or two. I keep the water bowl up for two hours after a meal. Giving ice cubes is a great way to give water slowly. If you're feeding wet food or hydrated dry food, they shouldn't need a whole lot anyways right after eating.
Keep him quiet after meals. No running or playing. Just relax.
After meals or during an upset, you can rub his stomach in a clockwise motion (if you're looking down on him with his head facing forward) to get everything moving in the right direction. I use a heating pad on the stomach to, set on low. This relaxes the muscles and keeps everything moving smoothly. Heating pads are especially helpful for upsets.
I hope your dog is feeling better soon! Just let me know if you have any additional questions.