Why do my eye lid kep on changing?

I am asian so I kind of have chinky eyes but I do have one little eyelid that starts from th corner of my eyes to the top. But when I rub my eyes with water it has 1 big eye lid and two faint ones in my right eye. In my left eye it isn't common for it to change but now it has 1 big eye lid and 1 faint eyelid. It normally changes back but now it hasn't. And can you Tell m why this happens and how to prevent it.