A few hours before I get a migraine I get very tired an fatigued. Why does that happen. No aura just really fatigued?

3 phases. Most folks with migraine experience three phases, the prodrome, headache itself, and post-dromal period. Each may be several hours, and your experience involves your prodromal initial experience prior to headache. Aura refers to "classical migraine" which is a variation of a pattern experienced by a select group of patients.
Variation of normal. Might be your body's particular way of producing an aura or just how your particular pattern is.
A prodrome symptom. Prodrome: subtle changes within one or two days preceding the attack. This may include constipation, depression, diarrhea, drowsiness, food cravings, or hyperactivity and irritability. Aura: are usually visual but can also be sensory, motor or verbal disturbances...For more info..Check out this lik, http://www.Mayoclinic.Com/health/migraine-aura/mm00659 .. Good luck.