I agree, at Ten weeks they begin teething. Shih Tzus though are known to have slight tempers and attitude. To help with the biting I recommend using something called Bitter Apple. Its a sour spray that you spray either in the dogs mouth, on what they bite, or on your finger. If you put in on your finger gently grasp the dogs muzzle and part its lips and rub the solution on the teeth or directly on the tounge. I too recommend obediance training. Best of luck.
Oh here is a link that may help.
http://www.canismajor.com/dog/shihtzu.html