Goldfish dropped and suffered head trauma

Question
My 7 year old son is heartbroken.  I dropped his goldfish "Silver" about 3 feet when transferring her back to her clean tank.  She has a bloody eye and some blood across the top.  Five hours later, she is now hanging along the bottom and listing to one side.  I have read many of the posts but now I am more confused than before.  She is in fresh clean water and I am keeping her in a dark area.  Anything else I can/should be doing?

Answer
Get some flow and aeration going asap.  I'd spend much longer on this answer, but her breathing is why she's on her side.  The head trauma can cause them not to be able to have bodily functions as simple as proper breathing and absorption of oxygen, so let's get a flow going asap, not heavy, just enough to move water through her gills, please.  Perhaps an air stone or bubbler....

Renee