What Causes Lack Of Concentration?

So I have been having a hard time concentrating in school and have been dazing off a lot. I'm not sure what to do about it and I want to treat myself. I brought it up to my parents but they just kind of brushed off. Should I go to a doctor when I'm 18 to see what they suggest? I've tried eating more breakfasts and going to bed early but its like everyday it's hard for me to do stuff like talk or read. Like I'm normal but I'm not sure if there's a problem or not.