I have two chins, Pika and Lilly. I got Pika in a pet store 8 months ago, Lilly from Craigslist two months ago. Pika was getting really stressed out so we decided to get her a playmate to see if it would help. When we got Lilly, the very first thing she did was start spraying. The previous owners mentioned this as well. We put them in two cages side by side, let them have playtime together. Whenever we got near Lilly's cage she would start grunting and spraying. Eventually they got friendly enough with each other that we were able to put them together in the big cage we had got them. They started out fine, a few dominance plays but nothing too bad, no fighting, no biting, they would curl up together. We let them adjust to the new cage, Pika got 1000 times friendlier, Lilly was still stand-offish. Now, about a month and a half later, we still can't get near the cage because of Lilly, she will grunt as you walk by, if you try to pet her she sprays, if you try to let her sniff you she sprays, if you give her treats she sprays, if you sit on the floor next to the cage she sprays. I've tried bribing her with treats, it worked at first but now she won't even take them, I've tried blowing on her when she sprays, she just sprays more.
She's started getting more aggressive towards Pika now too. If Pika is at the food dish before her, she sprays her, if Pika is in the bath house she sprays her, if Lilly is between ramps and Pika is trying to pass she starts grunting and gets aggressive, if Pika is running around while Lilly is sleeping she'll wake up and spray her. Lilly has also started trying to bite at our fingers and actually following the movement and snapping at them.
Is there anything I can do to calm her down? Would separating them help? I'm at the end of my rope, every bit of advice I've seen so far hasn't worked and makes her more aggressive. I'm just worried she'll start attacking Pika, Pika is about half her size.