What Causes Dizziness, Blurry Vision Followed By Fainting And Shaking Of Hands?

i have been having dizzy spells for a while now, my eyes go blurry and i get severe pressure in my head afterwards, but today i felt really dizzy, my vision went blurry and the next thing i knew i was on the florr and feellingm a bit of pain, my husband said he heard a bang and that my arm/hand was shaking, i'd had a fit, please help as i am really worried now.