What could be causing my extreme fatigue and bloatedness? and have mild cramping in my lower abdomen and back for about 2 days. my period is 12 days

12 day period ?: A period lasting for "12 days" , if this is a regular occurrence, may deplete you of hemoglobin, which leads to anemia, producing fatigue. The bloating may be caused by endometriosis/adenomyosis, so contact your gyn physician, and ask him/her to get a blood test for anemia, and explain endometriosis. Oral contraceptives may be a remedy for this situation.