This is NOT a normal post vaccination reaction and the kitten must be brought to the vet as soon as possible. Call he vet, explain what is going on an get that baby in. This is one of those emergencies that needs to be addressed with speed. Lethargy and a but of soreness is not uncommon after vaccines for a day or two, but this amount of vomitting really worries me. Call the vet. he has to be alerted to this.