I adopted a male kitten from a shelter two days ago. I'd been watching the litter grow for two weeks. The kitten I got didn't purr, but I didn't think anything of it until yesterday morning. I finally got him so happy he started purring. When he did his head/neck spasmed consistently until he stopped purring. It looked like he was jutting his chin forward. I haven't been able to get him to purr since.