I have two female guinea pigs. When I first introduced them to each other, it was pretty clear that CC was the dominant guinea pig and Poppy was the submissive one. They have been getting along up until a couple of days ago when Poppy started to express dominance towards CC. Both of them have been aggressively running around the cage, rumblestrutting, and attempting to mount each other. CC seems to be upset that Poppy suddenly decided that she wanted to be the dominant piggy. Is it normal for a piggy like Poppy to want a change in hierarchy? And how long should this behavior last until I decide that it's hopeless?