I'm so sorry about your fall and brain injury. I know it's frustrating and scary; I had a nasty fall several winters ago when I slipped on ice at the gas station. I hit my head on the metal gas pump and got a terrible knot. Went through weeks of having trouble with things that once came easily--matching things up, measuring, remembering how to do fractions. I healed , thank God, and pray you do as well. Hang in there.
Chances are, you will have an "aha" moment and will suddenly see why things are not lining up. If you're too frustrated, put it aside and do an easy thing for a bit. Putting pressure on yourself won't help; it adds to the brain wires messing up.