Hi Liu,
Don't want to keep going on at you but i just wanted to check that you haven't misunderstood what some of us have been saying.

I agree with you that the normal activity of playing basketball shouldn't be too bad. It might make you a bit dizzy, but then a lot of things make us dizzy and we can usually get better with a bit of rest. Exercise has been shown to be good for the brain so playing basketball might actually be a good thing for you in this sense.

The reason I advise you not to play it isn't because normal basketball would make you worse. What I am worried about is the next time you get hit on the head with the ball, collide with another player, fall over and hit your head on the floor or collide with a post.

The evidence, as well as the personal experience of myself and many others is that if you have had a concussion then future concussions will happen more easily, and will take longer to recover from. You have had a concussion just from heading a ball, so your next concussion could happen even more easily than that.

If you keep playing basketball then sooner or later you will definitely get a significant blow to the head. It doesn't matter how careful you are, this is just one of the things that happens in basketball. When that happens it is likely that the horrible experience you have had will return, but for longer, and with worse symptoms.

That is all I'm saying. Good luck with whatever you decide.