I second Janie's post, DS has some issues with a few food additives, the difference in him since we took them out of his diet has been huge.
As a mum I think you always have times where you have no idea! I have been a mum for 18 years next month and i think I know less now than when I started. The fact that you care and that you are asking questions means you are a great mum so never doubt yourself.