Sugar never barked/growled at anyone until the 9th month, her personality changed tremendously, she now loves to bark/growl... something like what you described. I couldn't find the reason, even after spayed, her personality remains the "naughty" side, never go back to the previous behaviour. I'm not sure Olive change of personality is permanent or temporary (like you mentioned you're sick and she wants to protect you), but I just know I still love Sugar so much although she doesn't like to meet people and barks a lot
