I've noticed that my little boy rat has started scratching behind his ears and his chin a lot lately. Today I noticed a little scab behind one of his ears that I suspect is from the scratching. I have had him since the beginning of December and I have noticed the extra scratching for about 2 weeks. I have not recently changed his type of food or type of bedding and other than the scratching, his behavior has been normal. I also noticed a little bit of dandruff on his fur for the past couple of days. Is there anything I could bathe him with to help his skin?