bonded gerbils fought

I’ve had two gerbils for nearly two years now, they’ve been completely fine with no fights even when their third brother died last year. I came home today to find them both bloody, one has a seemingly bald bloody patch on his face and the other is squinting a bit but is otherwise fine despite the blood. they’re both walking, drinking, and eating fine and they had a normal interaction when I saw them. this is my first time owning gerbils and my family cannot afford to take two injured gerbils to the vet, I don’t know what to do and I need to figure out a way to clean them and keep them from fighting again. the only thing different from usual today was their feeding time, I fed them later because I was rushing to school in the morning