HELP!

I got my first chin Dash around mid october. Then on November 28 I went to petco for some treats for Dash and saw a chin. They were adopting him out for free bc he had suffered an injury in the cage there and had nerve damage to one of his front legs. I brought him home and tried to do a side by side cage meeting. But then read to do cage within a cage approach. I did this for around a week and a half (I tried to introduce them during this time and Dash tried to chase and attack my new chin Fitz so i just continued with cage inside a cage approach). I took them into a neutral room and they didnt attack each other(only this first time), but if i try it in the room with the cage Dash again tries to attack. I tried to introduce them two more times in a neutral room and now my new chin Fitz barks and has even sprayed pee one time. As of right now they are back in two cages that are just side by side. I really want them to get along but i do not know what to do!



Note: while i was out of town for a few days due to my grandmother being in the hospital my roomate who was taking care of them and giving them each exercise time, accidently let them both get in the smaller cage and said they just hopped around and acted fine but when i came home i tried to let them meet again and Dash started chasing Fitz again :/. Also i have tried switching them from one cage to the other for awhile to get them used to each others scent.



Please help! Any advice is appreciated!