Changing Subjects?????????

Ok I got my new timetable for High Sch,ool, I was looking forward to it on Monday, but I took BAD stomach ache and got sent home. I have been off this whole week with it and now its almost gone; I'm worried now about the subjects. I don't know where to go; I don't know my teachers; I don't know who's in my class. I'm dreading this and I am worried sick. I start crying and shaking. I am worried I'll get into trouble for not going to the right classes... What should I do?????