Cat Suddenly Aggressive

Hi.
I have 3 cats. the last one we got 5 years ago, so he has lived peacefully with the 9 year old this whole time, as well as our 13 year old female.

anyway, last week the 9 year old attacked the 5 year old. sort of out of the blue, but it appeared that he got spooked when the 5 year old jumped out from behind a large piece of furniture.
this happened once before maybe 3 years ago, one morning, was better by night.

Now it has been 5 days and the 9 year old Bailey is still hissing , growling and freaking out when he sees EITHER of the other cats.

with me or my 3 kids, he is fine, let's us pet him, purring, acting totally normal, sleeping , eating well. (I am not seeing a vet for a medical exam)

I have kept him down in my laundry room overnights and up here during the days where he will stay in my room and maybe once or twice a day, they bump into each other and the growling, hissing and attacking occurs again. i will say it is definetly a little less violent and shorter lasting, but not much.
as far as the laundry room, they sleep down there maybe 1-2 times a week anyway, since there are nights I need good sleep and if they are up here they wake us at 4-5 am, so it's not new or scary to him.
I read to keep them apart for a few weeks then slowly re introduce them. I am not sure what to do.
I tried to feed them all at once, the 9 year old growled through his whole meal making the other 2 leave.
and now the sweetest cat ever, the 13 year old starting pooping once a day in my bathtub! UGH, but only started the day the boys fought so I am assuming that is stress and she doesn't want to go near the aggressive one right now.

any suggestions? I was thinking CBD oil? at this point valium may do! hahah j/k more for me than the cats.

Hi. All the cats are becoming stressed out from what is going on. The first thing I would have recommended would be to the have, at least, the 9 year old checked out by a vet, since the aggression started with him. Many times such behavior turns out to be health related. He is reaching senior stage and should be seen at least once a year with a full senior check up and blood panel. He is nearing the age where health issues can crop up. However, you have ruled out taking him - or any of them to a vet...

So, the only other thing I can offer you would be for you take a look at the article linked below and see if it might help identifies possible reasons for the change. Not all of the information in this article applies, but there is a section about cats attacking other pets/cats.

You could also try calming products on the cats to see if that helps, there are number of them on the market. One such product is Bach Rescue Remedy, which are drops you can rub into a cat's ear to help calm them. A lot of people use them before taking a cat to the vet to help with anxiety. You might have to try more than one of these products, as not all of them work on all cats.

Why Do Cats Attack?

It sounds like re-directed aggression, so there may be something helpful in this TCS article: Re-directed Aggression In Cats

Id recommend a vet check, other calming products are Feliway and Sentry (plug in difusers and collars as well as sprays are available) if the aggression keeps up you may have to reintroduce them

Thanks! will read those articles! we are on day 5 now and it's getting a bit better.....

I also did find an article from ASPCA recommending separating them for a few weeks and introducing gradually...I am keeping the away from each other at night for now....