Yeah you have to enjoy the game, play what you are able to. If you're tired, stop play and if you feel like playing just play
It's really hard to believe you have 50k pc and didn't improve in the past mounths since i improved so freaking much in just 20k plays
You may have forced yourself too much, that's just a game and i don't think you thought about this like that. It also happens to me sometimes but i just get bad and can't play properly when i'm mad cause of miss, sliderb or anything else (pretending to fc things that are just too hard for me at the moment, etc..). You need to think positive and don't run, many pro players played for many years so you probably don't have a correct perception of the time you need for improve the much you want to.
It also depends from player to player since somehow improving at osu! is something physical