Sore Nose More Condition_symptoms My Gerbil Appears To Have A Sore, Bloody Nose. What Could Be Wrong With Him?

My gerbil appears to have a sore, bloody nose. What could be wrong with him? - sore nose more condition_symptoms

I realized one of my gerbil has a swollen nose, dried blood. There seems a certain time, but it did not. What could be causing this and should I worry? It seems always the same something other than fighting / fighting game with my gerbil a different time, perhaps the cause could be?