My dog is sick, what should I do?

My dog threw up seven times all over my house. He is a shit-zhu (spelling may be wrong) and he’s a year old. He seems to be pretty weak, and every time he threw up he looked like he was going to collapse. He’s sleeping now but he may get sick again. I’m worried he might get dehydrated but he won’t take a drink of water. What should I do, I’m so worried about him.