I suddenly keep losing at chess. What do I do?
Whenever you lose a game, stop playing and analyse it first to learn from your mistakes and to channel the negative emotion of the loss into a positive goal of improving.

It's like the stock market. Your ELO will trend upward over time. There will be ups and downs on the way.

FIDE and national association give zero value to chess.cos ratings, and neither should you.
Have the mentally that the site’s rating is not a real rating, and just focus on doing less blunders and study your games.