High School Academic Records for SA

I am going to enter a service academy and used a 504 plan in high school, but never disclosed on DoDMERB as they did not specifically ask for it. I heard that all paid military jobs require a security clearance. I am wondering, as I am not even in college yet, if the security clearance goes all the way back to high school. And if so, does the security clearance ask for high school student records? Will my 504 plan and ADD diagnosis in high school be revealed through this?