My dog, Nolan, is a little over a year and a half and is healthy overall. I don't think this is a vaccination reaction, but a few days ago, he got his annual parvo/distemper shots. I noticed today that he seems to have painful bumps on his back and yelps when I pet him. I can't see any bumps, but his hair sticks up as if there are. He's been lethargic all day and didn't eat or drink until late in the evening. He also started having intermittent tremors, but that stopped after about 15 minutes. He still gets excited about playing and going for walks and I can tell he wants to, but he can't seem to manage to get up without a lot of effort.  He also doesn't stand for longer than a few seconds and it takes a lot of coercing to get him up. There's no vomiting and his stool is normal. I called the vet and she thinks that it may be a bite from something, but it seems to be a bit more serious than that. I'm afraid that he may have a dislocated disc or worse. Has anyone else had similar symptoms or issues?