What Causes Bruising On Face And Cheeks After A Head Injury?

I fainted 6 days ago and banged my head quite badly. The doctors in hospital said my blood sugars were low
I started to get a blck eye 2-3 days later and bruising down my face and cheek on 1 side. The bump on my head is so sore and soft.
I keep going dizzy and have blurred vision and nausea on and off
What is this caused by and what should i do?