What Causes Poor Memory After A Head Injury?

My dad, who is 79, fell and hospitalized for 2 days now w/concussion and a little bleeding on brain. The neurologist wasn t overly concerned because it s such a small amount. We re concerned because he can t recall things correctly. Even thinks president is Woodrow Wilson...is that normal?? Again, the neurologist says this is normal and that he should be getting back to normal in about a week. We ve never seen him like this before! Help!