For some months, I have tried to rank my some keywords. Finally, I got first page 3, 4, 5, 6 rank position in Google. But in this month my rank position fall or down. I know somebody is using my keywords and URL for falling or decrease my rank. They try to their best to decrease my rank. But, it's really very harmful to me. I want to protect their activities. Have any process? How can I stop the enemy's activities?