My child in middle school suddenly this symptom. After each meal, no matter what is the food (vegetables, fruits, grains and meat), she feels sudden nausea / fullness and then (in a few minutes) headache and then strong dizziness.
If she does not eat, these problems do not appear or very light. After each meal these problems appear almost immediately. It has been like this for a month and she has to be home lying in the bed. When she stands, she will fall off to ground.
One day, she went out without eating, it seems scything is fine.
Thank you very much for an input.