My dog throw up three times today, he has a loss of appetite, and is slightly fatigue, he still wanted to go outside but is always laying down, when normally he is very energetic.
The gold standard for treatment vomiting in a dog is fasting. Generally vomiting is acute (meaning it comes on quickly) and can be taken care of without much trouble.
If this were my dog, I'd fast him for 24 hours (providing he doesn't have any underlying diseases such as diabetes that require he eat every few hours). No treats, no food, nothing. You can leave a small amount of water available, but don't allow him to drink too much at one time (placing ice cubes in his bowl so that he can't gulp water will help).
After the 24 hours, I'd offer a bland diet of boiled rice and boiled hamburger (3 parts rice to 1 part burger) in VERY small amounts (perhaps 1/4 c every hour or so) for the next 24 hours. Once you start feeding the rice mixture, monitor the dog for recurring vomiting. If the vomiting doesn't start again, you can begin slowly mix in his kibble over the next few days until you're back to just kibble.
If the vomiting persists for more than another day or so, or if your dog becomes lethargic, begins to have diarrhea or shows other 'unusual' signs, you should have him seen by a vet, just to rule out any sort of illness or parasite infection.
I hope this helps!