I am fostering a mother cat of only two kittens rescued from a shelter. The mom loves to be pet, but then will suddenly strike and scratch. She does this even when I walk by and am not touching her. She growls and paces a lot too. She's not feral ... also I can't afford the non-aggression spray feliway... I'm a little frustrated because she also won't tolerate me trying to pet her kittens. So any suggestions?