Cold From Shots?

Thursday Bagheera went in for his last set of kitten shots. He was fine until yesterday. He started making really funky noises. Rattling in his chest, Breathing funny and just acting very lethargic. I called the vet at her house and asked about it. She said it was probably just a cold caused by a shot. I never heard of that. She said the name but now I cant remember. Its the one they shoot up their nose. Anyways she said to bring him in today but when I got there they said she wasnt working today. The other vet just held him for a second and said that if he wasnt better by wenseday to bring him back in and my regular vet would give him meds. He is acting ok today. Playing a little but still breathing bad. The vet is closed tomorow. I dont know if I should worry to much about it. The vets didnt seem to concerened either one of them. Has anyone experienced this?