fell on ice straight back hit back of head
Welcome to the neurology medhelp forum with this query. you had a head injury following which there could have been an intracranial bleed, the hematoma could be causing the pain in the head and irritating the nerve supplying the area causing numbness. I can see that you didn’t have any of the serious signs like dizziness, loss of consciousness, slurring of speech, drooling of saliva, visual and speech disturbances etc. you should go meet a neurosurgeon at the earliest who would do a CTscan head to rule out any bleed that could cause compressive signs or any fracture skull . Do not wait and watch, instead take immediate medical help.
I hope this helps. Please feel free to contact me again for any other clarification.