EXTREMELY stressed out - TC not getting along with Luna

For the past few weeks, Top Cat (TC) has been acting like Luna is his worst enemy. It mostly started when I took Luna home from her dental visit. His tail puffed up twice his size and he started growing at her like he never met her before. He even started to make weird aggressive sounds and tried to start several fights with her. I figured the strange smells were upsetting him and he would calm down. It took him a few days to calm down. But then a couple of days later, he started acting really aggressive toward her again, growing and screaming and chasing her.

Finally, I got so stressed that last Saturday (a week ago), I took him to the vet. He was behind on his shots, so we got those taken care of and talked to the vet (who was an associate doctor that fills in around there) who discussed doing some things, but was going to give things more time when suddenly TC turned around fast and bit me in the face. His tone changed quickly. He gave me the business card for the behaviorist associated with them. Mom and I called her that afternoon and we got her to come over today.

She gave us some suggestions such as adding an extra litter box (which mom was real resistant to, but I convinced her to let me do it anyway) and we are going to consult a friend to help us (we'll pay him of course) construct an enclosure for the patio deck for one of the cats (right now there's a cat tent out there that I've been putting TC in during the day to protect Luna, now he also has the bathroom set up indoors for him).

Now we did get another cat recently but the behavior did not start until days after when I took Luna home from the deck. The third cat stays towards the back of our house in a spare room set up for her and I haven't started introductions for her yet (I need to worry about reintroducing TC and Luna now even though they've been living together since TC was a baby).

But even tonight, with the door to Luna's room close and the bathroom door open (only one cat can roam the house at a time now), TC was still trying fight Luna through the door. Even more sad is that Luna doesn't cuddle with me on the bed anymore. She spends the whole night hiding in the closet. I hope now that TC will be separated all day from her that she will sleep with me again at night. It breaks my heart right now that she isn't acting the same because of him.

No hissing so far today, but the cats are still 100% separated from each other. Only one cat is allowed free at a time. TC gets the most free time since he has the bathroom as his room (the girls each have a bigger room with windows to stay in) and he is very active. It is still very stressful for me. I have to deal with full time classes, full time work, and then this. Sometimes, I feel like throwing in the towel. It is very emotionally exhausting.

well, I took TC back to the vet and they gave me some medicine to try for him. Also, the vet wants to test to check his thyroid levels to make sure that isn't causing his aggression. But we will try the medicine in the meantime because I am very stressed with this cat situation. Luna still has to be separated from him because she is afraid of him.

I have the feliway plug in in my room (also Luna's room) since a week before the behaviorist came and I kept TC separated 24/7 as well as the calming collar on TC. Right now it seems like they do nothing.

If it helps figure out anything, TC did lose quite some weight when I took him to the vet. I thought he looked skinnier. He was 11.4 last year, this year he is only 10.4. But I thought I weighed him in between that time and he came up over 12 lbs. But my memory is foggy on that. His waist is definitely slimmer.

so far nothing seems to be working for TC. Also, Luna now hates him as well. She hisses at him even through the doorway (Luna stays in my room when he is let free throughout the house). It is almost two weeks since we started the medicine on him and I am waiting for him to start to show improvement.