Suggest Treatment For Headache At The Back After Injury

hi last night at about 11.30 i banged the back of my head on the wall i was drunk at the time and i do feel a bit light headed now but im guessing that hangover of the drink i do have a bit of a pain there were i hit it and more when i get up is normall and what should i watch out for and there is no lump or anything :/