hi duncan
glad you are feeling a little better and you have seen your doc, I remember when I was young, I had one of those 1970s chopper bikes with the small wheel on the front I went down a pot hole , and over the handle bar and hit my head on the pavement I think it was a month or so before I felt back to normal, you probably have whip lash coz your head bounced down the stairs ( I know they an,t cool but cycle helmets are worth waring if you are jumping down stairs ) I have a bad head injury, so dont worry you will most likely keep improving with time please keep us posted on your progress

kind regards Vini