visit godairyfree.com. GREAT website that has TONS of info about dairy .. where to find it ... how to avoid it ... recipes that have super substitutions!
beware of things that say they are 'dairy free' ... that doesn't ALWAYS mean that there is honestly not a hint of dairy. words to look for: casein, caseinate, lactose, whey, milk, butter, yogart, some forms of calcium lactylate, etc. (see that website for a complete list) the only margarine that i have found that tastes good, we can afford, and is suitable for cooking/'baking is Fleishmans UNSALTED margarine.
my daughter has a dairy allergy and she had a CHRONIC drippy nose, sinus infection, snore, sore throat, ezcema, etc. (in addition to lots of other problems!) when we figured out the problem and TOTALLY eliminated ALL dairy she cleared right up.
good luck to you.