Post menstrual dizziness every month. could it be estrogen dominance or endometriosis?

Possibly: I'm not aware of a direct association with either but both can cause either excess bleeding, pain or both, leading to a low vascular volume or over production of a hormone called prostaglandin which can cause nausea, diarrhea, and again secondary dizziness. Something else to consider, atypical migraines. These may cause neurological symptoms without a headache & occur with your cycle.