Maybe it makes sense to try some food eliminations? Some of the foods that seem to cause problems for some of us are nightshades, soy, dairy, eggs, and corn. There are probably others I am not thinking of right now. Anyhow, some of the other food intolerances can cause fainting symptoms for some people. An elimination diet can help you determine if it is a food related issue. A mistake people sometimes make is thinking elimination diets are about eating less food. They are really about eating fewer foods, but as much of those foods as you want.