>>473
as a kid I used to get good grades without studying and teachers would always say I was good and smart, but once I got out of school I realized that the same tests were getting easier year after year so my government could increase the passing rates and pretend their education policy was good, and I just was a bit smarter than very very dumb people rather than being actually smart
I've gotten a lot worse over time too, just like you, to the point it's genuinely debilitating and handicaps me in my daily life, I can't remember things, communicating is very hard, and even the things I know I could do are now impossible because I'm unable to focus or to hold my attention anymore, the only thinking i can do is justifying my emotions and being a braindead shut-in neet in current year only gives me negative emotions
it's rough sometimes
>I've tried to read some grammar books so i can improve
I strongly recommend reading actual books, fiction or nonfiction
grammar books are great and you should have one, but regular books do just as much while being a lot more fun to read, you can just passively absorb some of the rules and new words while enjoying a story or discovering fun things