J.,
My first thought is a food allergy of some sort. Since it started well before solids would be introduced it must be something in your diet. It may be hard, but elimination dietrs work best. Start by removing one item every 4 days from your diet, the most commom allergens are dairy and eggs. Be sure that if you did not make something from scratch that you read the labels very carefully so that you are not accidentally adding somehting back into your diet.
SOmething else that you may want to consider is the chemicals that you use to clean everything from the dishes to the laundry. After two weeks, I bet you did laundry, he may be sensitive to the chemicals that you use in the house. Did you know that there are more chemicals in the average kitchen than there were in a well stocked chemistry lab in the 20th century!
If you would like to try non-toxic products, that won't harm you and are less expensive to use, email me ____@____.com