Why did my score go from a low 1200 to 1350?

not looking forward to needing to lose 15 games in a row to get it back to normal. Also, a window popped up saying "another login has been detected" but there's nothing unusual in my game record.

Chess.com artificially inflated your standard rating (and all standard ratings in your range) by 150 points in order to fight deflation that they noticed.

deflation? hmm. How does that happen?

because the opponent went down.

what do you mean by deflation?  I think another login detected can happen if you have, your chess browser open on your computer, and the app on your phone at the same time.  This happened to me.

Because you don't know how to read.

        Thank god he's on a chess site and NOT driving on the highways.

I found this which explains the rating changes.

http://www.chess.com/forum/view/livechess/standard-ratings-boost

http://www.chess.com/forum/view/livechess/huge-rating-jump                              http://www.chess.com/forum/view/suggestions/standard-ratings-corrupted  http://www.chess.com/forum/view/general/my-standard-rating-grew-without-me-playing      http://www.chess.com/forum/view/general/my-rating7                               http://www.chess.com/forum/view/community/sudden-increase-in-rating          http://www.chess.com/forum/view/livechess/why-did-my-ranking-jump-over-100-points         http://www.chess.com/forum/view/general/chess-rating-suddenly-increased       http://www.chess.com/forum/view/help-support/chess-rating-jump               9 THREADS    HELLO