Hello there,
Good to hear that things have settled down for the moment. It is very worrying when things don’t seem to be working. Especially when the alternative is either saying goodbye to the new pig or having to get another cage. I think we all know those things take up a lot of room!
Now, of course no one here can MAKE you do anything, forum members can only talk about what they believe, or know from similar experiences that you should do. You may not be keen or able to get another, or bigger cage, but if nothing else, then at least it’s worth having a look online to see what options are out there, or by asking forum members for recommendations on which cages work for them. You might decide you like one of those better and that would give your pigs much more room and happiness, which I’m sure is what you want for them, or else you would have never posted for advice.
There are also wonderful threads on toys and homemade boredom breakers and things to keep them busy in the cage so they have something to do other than respond to their crazy hormones right now, or when the next flare up happens. A bigger cage would allow for more hides/houses, maybe cardboard boxes filled with hay, tunnels (they love tunnels) and several different food bowls so they don’t have a disagreement about who eats when.
Also, a nice large cage filled with fun items is a nice thing to have in your house. It’s nice for people to look at and you will have hours of fun watching your guinea pigs being so happy and busy. So although you may not want to get a new cage, it won’t do any harm to have a look and will definitely be worth it in the long run. Plus, it’s really exciting to plan a new setup! There are guinea pig ‘cage tours’ on YouTube which are good to watch for ideas.
Of course, as people have warned, there is the possibility for a fight to the death if your pigs continue to not get along. Hormone flare ups will come and go as they creep towards adulthood, so please do make sure to monitor them carefully and be prepared to remove the new pig if things get too ferocious. He needs you to look out for him and be his protector, as he won’t be able to get away from his cage mates in the event of a huge fight without you there to step in and rescue him.
I’m sure you love your guinea pigs and sometimes the best thing for them isn’t the easiest, cheapest or most preferable option, but unfortunately that is part of our job as pet owners and the promise we make when we take on a little life.
Wishing you the best of luck with your situation.