Thanks for posting your query.
As you are having adenomyosis
so bleeding heavily and pain. Due to excessive blood loss your body becomes dehydrated and anemia occurs,it may lower you blood pressure, then it may present like light headedness and fainting. You should treat adnomyosis and stop excessive blood loss, if you can tolerate hormone treatment then you may choose Endometrial ablation
or Uterine artery embolization
You should take large amount of water and healthy diet. Use folic acid
, iron and other vitamin supplements to build new blood fastly.
You can visit your doctor and check your hemoglobin
levels and blood pressure.
Hope it helps.