Wow, that's scary :shock: I'm so sorry you are having such trouble with your rats. I've personally have never experienced rat's having a nosebleed but I looked it up and ratfanclub.org recommend: Bleeding from Nose, Ear or Mouth
Bleeding from inside the nose or ear is most commonly caused by an infection, which can erode away the tissue, opening a blood vessel. The size and number of the vessels determines the amount of bleeding. Nasal infections are difficult to treat and require aggressive antibiotic therapy. For bleeding from the nose, you can try holding ice to the bridge of the nose. You can also give your rat ice cream or a popsicle to eat, and hopefully the cold will penetrate the nose and help.
Bleeding from inside the mouth can also be difficult to deal with since itâs so hard to see where the blood may be coming from. Itâs possible for a rat to accidently bite his tongue, and bleeding can also occur from a mouth tumor or from an injury to or tumor in the throat. Giving your rat ice cream or a popsicle may help stop the bleeding.
For bleeding from an ear, try putting pressure and/or ice against the base of the ear. Infection or cancer are the most common causes of bleeding from inside the ear, but occasionally a rat will accidently puncture his eardrum while cleaning his ear with his toenails.
If you cannot stop the bleeding after trying all these methods, you will need to take your rat to the vet where he can anesthetized for more effective procedures, such as suturing. There is also a product called Gel Foam which is a protein that becomes very sticky on contact with blood which may be able to stop bleeding from an injury. Your vet can also give a rat an injection of vitamin K to help blood clotting.
but I would recommend getting the rat to the vet as soon as possible
Good Luck