What Causes Fever,lethargy And Missed Period?

starting I had a 3 day migraine 10 days ago followed by crushing fatigue followed by a fever that fluctuates between 100 and 102 for the past three days and nights. I've ruled out the flu b/c don't have the cold symptoms or the stomach upset just feverish body aches, sensitive skin, and abdominal cramping similar to ovulation or starting period. December skipped period. Having many migraines. Not using any meds/hormones. Is it common to have a fever with lethargy under these conditions?