I've spontaneously unlearned how to play League.

My winrate over the past 20 games is a measly 20%. This includes some ARAM games, too, and it's a record over the past two weeks.

The numbers speak for themselves. While I was a decent midlaner and jungler before the year changed (I had a 71% winrate on Lissandra over 30+ games), I've spontaneously unlearned how to play League ever since January. My Ranked winrate is 31%, showing I am absolute garbage and don't belong in Platinum V. Much less Platinum I where I peaked last season.

In these sort of situations, what are the best things you can do? Sometimes it feels like my performance is just fine, but that every other lane just loses! And obviously, this can be true for a few games, but I doubt it explains 20%.

Is Swain just really that bad? Maybe, but not 20% bad. I lose with every champion I play anyway.

So it must mean I'm bad. Very, very bad.

How to fix my own badness and get back into playing League properly again?