I got a new friend for Shelly about a week ago. After quarantine, I tried introducing them. I put them Ina play pin with a sheet underneath, and at first they didn't do anything, then Shelly started nipping at the new one (Quin). After about 45 minutes of Shelly mildly bulling Quin, I took them out and put them in separate cages next to each other. After two more days of doing that, I put them in the bath tub together (no water) and Shelly was worse than ever! She was nipping, teeth chattering, chasing, and sniffing poor Quin. Quin was squeeling her head off, and I thought Shelly was going to bite her! Any tips?