i am confused. My ecommerce website. Why is it that sometimes I rank 1st page for product keywords, lots of them and I get a lot of traffic, then sometimes I can never be found anywhere in Google for the same keywords, then about 1 month later I'm back ranking high again.. It seems to go back and forth back and forth between ranking high and low and usually I don't do anything in between to make it rank HIGH or LOW??????????? Could a competitor be doing this somehow? What is going on?