Urine stain on fur

Hi. I am a new chin mom for about a week. A few days ago, I decided to switch to fleece lining when I got the FN cage (I used aspen shaving before in a smaller cage when I first got Candy). Very quickly, I started smelling urine from the cage and recently on Candy as well. Then last night, I noticed that she's got something that looks like urine stain on her bottom part (yellow/orangish color) when she stood up. She also licks that area occasionally. I am hoping it's just simple urine stain (she is not pottery trained yet and is only 11 weeks old), but I am concerned about the fact that she smells a bit (again, could be b/c of urine on her). She still eats and plays. Should I be concerned about possible urinary tract infection/kidney stone, etc.? How can I get rid of the stain on her fur? She's so young and new and we are just beginning to bond so she wouldn't let me pet her much, let alone hold her (it's very hard to catch her w/t scaring her off too) so it may be hard for me to wipe it off her. Any advice would be greatly appreciated! Thanks!