When do you see the flashing lights? If they show up just as you're falling asleep, and appear when your eyes are closed, this is normal and is called a "visual sleep start". If you're seeing them at other times, it could be something going on with your eyes that would warrant a call to an eye doctor. Or it could be psychiatric or neurological.

As for the "ghostly images" - not sure what to make of that. Do others see them? Again, it could be visual, it could be psychiatric...it could even be paranormal if you believe in that sort of thing. Do the images only appear in one setting or in one light source? Or are you seeing these things everywhere? So many things it could be. I'd give your pnurse a call, just to let her know since it is causing you distress.