Can they expel me from school before leaving cert?

I got Suspended/expeled from school today becasue i came in 2 hours late,and i did it often.I have been going in late becasue of personal reasons or health issues,but i never brought in notes from doctor or parents,neither do parent know about it,so i have leaving cert at 8th of june and the suspended/expeled me tilL that time.Is it allowed to do that just before exams like that? I told the deputy principal,Ill go to doctor get a note she said no your not going back in,i said see you tomarrow it wil be official,shes a real *****.