My pet mouse wont stop biting me, and he is drawing blood.?

My pet mouse will not stop biting me, at first he was just nipping, but then he really bit me and drew a little blood, and after that he bit me one more time and it drew a lot of blood. I'm fine, and the bits are not infected. I got him and another mouse almost three weeks ago. The other one is nice and so sweet, they were in a cage together but the mean one wouldn't stop biting him, so I had to separate them because the nice one was getting scabs on his back. They are both male, and both have red eyes. the mean one is brown and the other is white. And there is one more thing, they came from two separate cages. I know the size of the cage does not matter because I left the white one in a big cage and left the brown one in the smaller one they were first in together. And after I let them cool off for about four days I put the brown one in with the other and his started acting ok, then about a half hour later he went back to biting. I am trying very hard to handle the brown one , but he constantly bites and gets irritated easily. They have plenty of food and plenty of space. They even get some fruit every day, they have it good. I even let them interact out of the cages, i've read everything I could find online, I'm stumped.