The first thing I'd recommend is a trip to the veterinarian and a full checkup for both cats, particularly bloodwork and - for Dorito - a neurological examination. Sometimes hissy-pissy outbursts that come out of nowhere can have a physical cause. Since a physical problem can be life-threatening, it is best to eliminate medical issues first, then worry about a behavioral issue. (I'm assuming here that both cats are spayed and kept indoors. If not, you should correct these situations at once.)

If your veterinarian gives both cats a clean bill of health, the best thing you can do is make sure both cats have plenty of space, then let them work it out on their own. Cat fights are generally noisy but not lethal. The screaming sounds awful, but remember if that mouth is busy yelling it isn't biting.

Make sure the litterbox is scooped daily and changed fairly often. You might want to consider a second litterbox if you don't already have two. Remember to take fresh stool samples to your vet, and if you can get a clean urine sample that will also help the vet with his/her diagnostics. Be sure to mention that urine smell to the vet, it could indicate a bladder infection or other physical problem.

Also, think hard about when the problem started. Did anything change in your apartment during the week leading up to the first explosion? Sometimes something as insignificant as a new piece of furniture, new cleaning product, new perfume or new brand of cat food can rock the very foundations of a cats universe. Remember that your apartment is their whole world, something that is barely noticable to you could be earthshaking to the cat.