Someone please tell me what my ranked stats are about?

So yesterday I played a game and I was in Gold IV, somewhere around 17 LP. Today I played a game and won and it says hey "Congratulations" you've got one extra win and you are in Silver 1 with an additional win? So I am now Silver 1 with 2 wins?? Ehhh I was gold yesterday, not to mention I was Platinum a whole season ago?