Why does my son have migraine symptoms after losing 18 pounds in two and half months through dieting and exercise?

Hello doctor,

This is regarding my son, who is of age 16 years old. He started dieting in the past few months (without our information). He did not eat or drink enough water or food for that time. He also undertook track and field (running) - three miles every day. As a result, he lost about 18 pounds in two and a half months.

But later, we noticed that he had developed some migraine-type of symptoms. The migraine symptoms are:

1. It mainly occurs early in the morning, watching television or eating food, but it is random.
2. The duration is about 10 to 15 seconds.
3. Sometimes it does not occur for a day or two. Then again happens once or twice a day.
4. He gets stunned for about 10 to 15 seconds and then returns to normal. It is accompanied by a mild to medium headache. Sometimes there is no headache.

Everything else is normal, like sleep, memory, alertness, etc. His height is also increasing as he is in his teens. We noticed this problem for six months and then took him to the family doctor. The doctor said there was nothing wrong that he could find. His eye test is also normal. We did complete urine and blood testing. It is all normal. I need help understanding what this might be and what needs to be done. Is there any general but useful nutrient that we can give to him?