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We have many unique domains - websites that we built - that point directly back to our SEO page. Some of these are fairly highly ranked sites.... Just guessing..... these links sound like they are placed in the footers of websites that are topically unrelated to the keywords that you are optimizing for?  If that is the case then these links are not worth as much as links placed with in paragraph text on relevant websites. If your rankings have dropped from #2 to #8 in just a few weeks it sounds like some of your links have recently been removed, devalued or an algo change has changed something.