Some cats just do not like being pet, it is just too much stimulation for them. Also, be aware that cats can and do purr when they are in pain. So, if this is something out of the ordinary for this cat, you may want to have it checked by your vet. One of my Pixie Bobs acts this way. She will come up to me purring and meowing her heart out, but when you pet her or try to pick her up, she growls and has a hissy fit. But, she has been doing this as a kitten. She just has an attitude and she is spoiled. She will let you hold and pet her when she feels like it and no other time.