Waking Up With A Stuffy Nose

I want to ask something .. Yesterday I woke up with a stuffy nose and in the evening I slept with wet hair in a braid .. I think it's because of that .. it's probably something from the period, because it's still a period of flu. So if I had a stuffy nose, I sneezed, I had skirts, but nothing else made sense to me, I hadn't dropped out, I went to dances, on my birthday and so on, the question is that I hadn't dropped out. Today when I woke up my nose was blocked again but I had not dropped out. Gradually I became very tired, once I felt dizzy, I can't stand on my feet. I want to ask if it's because I didn't eat at lunch and only now at 15 or so? Or is it just the flu? Tomorrow, if it's like that again, I won't go to school, I can't stand on my feet :( TIP? I'm 13 years old.