When Molly was a 8 wks puppy she was sweet and loving. Then the teething started and her playing got rougher and I guess I went a long with it (bad choice!) Now she is 4 months old and plays really rough biting starting to hurt a little bit so I know her teeth have definitely come in. What can I do to make her calm down and not be so aggresively mean? I'm not blaming her one bit, I'm blaming myself because I let it get this far but now it needs to stop. How can I correct this problem?