What Causes Headaches Along With Purple Spots In Vision?

My 8 year old daughter has complained of headaches when waking up in the morning for the last two weeks. For the last 4 days, she now complains of seeing purple spots with the headache in the mornings. The headaches normally last for a couple of hours, then go away by afternoon. I took her to the doctor and the doctor was unable to visualize her optic disc, even after several long timed attempts. What could this mean?