Puppy Sick After Getting Shots?

My 8 week Chihuahua just had her first round of shots. Two days later she has no energy, lethargy, and is trying to vomit and clear liquid came up but very little. It's like dry heaving. She finally had a bowel movement 24 hours later and it was solid. She finally took sips of water. She got ahold of some table food. What could the problem be?