What Causes Fatigue And Light Headedness Along With Frontal Headache?

my 19 year old daughter, fit and perfect weight.. eats very well and healthy.. fainting and lightheady and frontal headache mild but ibrufen or paracetamol don't help apparently episodes mid morning these last 3 weeks feels it happening but has passed out 3/4 times for 10 secs luckily in a safe area then fine, has done exercise classes 3 times aweek plus runs 5k 1 aweek never felt faint after these exertions ie heart under pressure.. eats a good breakfast toast yogurt tea and doctor heard a heart murmer and it to see cardiologist in 2 weeks, blood tested came back and normal no anaemia.. also no pregnant ? yesterday .. so a bit concerned ? advice be grateful :)