If i'm not pregnant, then what do you think is wrong with me?

i've been showing the signs of being preg but i haven't missed a period yet and i'm suppost to have it tomarrow, i took a preg test this morning and it was a nag. I've been feeling sick to my stomach,headach's every now and then, i get dizzy, have some cravings,my hurt,ect.. but i have been eating crackers, healthy food and drinking ginger ale. but if i'm not preg what do you think is wrong with me? do i have the flu or something?