How do i controle my ADD?

hi am caleb, i amm elevan years old and i was diognosed with add when i was 5. i find that being add is hard beacause i will be working at school when all of the suddon i will get the erge to do somthing else, for example i will be working on a worksheet that will say a word such as rain or any other word then i well start thinking about the rain like, how does rain come to be , how does the atmospher controle the water and thins like that , and then when i try to block out thinking about it it seems as if im going insane. i will start to twitch by moving my head from side to side and then people look at me like im crazy and then when i try to stop twitching i start to get realy tence and cant consentrate. I am curently taking medicen to help me with this but it doesnt always work, sometime i like to listen to music or doodle on my paper when im working ( wich realy works) but i cant do that when im in class so if there is anyone else out there who has ADD like me please tell me how u learn to control this......