I lost about 400 ELO (from 1016 to 600) in about a week and I don't know what to do.

I feel like I'm fed up with chess and played too much of it, but at the same time I just can't not play chess. When I do, however, it's not even fun.

I know I need to stop playing for a while but I just can't resist the urge. Also I feel very upset after losing ELO so fast despite the fact that I play chess just because it's fun and don't plan on making a chess career.

What can I do?

Don't worry l, keep calm, first step you need to enjoy the game again. If is only for you continue play bad. Make pluzzes all day, study chess problems, read one or two books for beginners. The idea is whit the book understand the concept of chess, the puzzle and problems chess is for have more power to calculate

Improving at chess is usually not easy. If you can afford few lessons, I would advise getting a coach. I can teach you how to think during the chess game. After that, your progress is inevitable.

If you can't afford any lessons, here is the excerpt from very good article on how to improve:

Play a lot, analyze your games, and primarily study tactics. Your knowledge of openings, endgame, middlegame, etc. will come from analyzing your games and going over grandmaster games. Only study one of those specific topics if it is clear you are specifically losing because of that topic.

Source: https://www.gautamnarula.com/how-to-get-good-at-chess-fast/

Here is the great YT series from my channel to learn from as well: https://www.youtube.com/playlist?list=PLUrgfsyInqNa1S4i8DsGJwzx1Uhn2AqlT

Good luck either way!