Does Attention-Deficit Hyperactivity Disorder serve as an excuse for bad grades?

I am uttrely incapable of sitting trough class or doing homework,I can't even eat normaly,I'm always on the move,my school has been getting worse,even when I try to read,I just lose focus after 10 seconds,and now I'll probably go for a correctional test on math,which I can't take,cause I havent studied in the last few years and I barely dodged the F's,but now I finally failed 100% and I'll probably repeat 11th grade,which is sooo humiliating and I can't take that.Is there any way to tell the teachers that it's just so hard for me to study.I'm otherwise very intelligent and I learn stuff instantly as long as it has interest for me(math has no interest for me,so I can't focus on it)