I have a pretty young guinea pig that has one ear that is dry and crusty. There isn't any apparent sores and he lets me rub it, so it obviously isn't causing him any pain. Is there anything that I can put on it so that it can return to normal? Maybe a drop or two of baby oil?? Any suggestions would be helpful, as this is the only guinea pig of my 8 that has had something like this occur. Thanks in advance.