I am the "allergy queen" full of knowledge. My DH has been gluten and dairy free for the past 30+ years.
If you suspect an allergy. Stay off of the item (all aspects of it----look for the word "casein" if you are trying to check for dairy).----stay off of the item for 7 days then "sock it to yourself." In the case of dairy-----on the 8th day eat yogurt, ice cream, milk, creamed soups, anything with dairy in it.... Then wait 48 hours for any effects...
Tested our young son for a dairy allergy and by the 4th hour on the first day of eating dairy, he ended up in the bathroom in bad shape. SO---no dairy for him unless he eat LACTAID first.
As for lunches, what about turkey roll-ups...or applesauce, fruit, chicken salad, egg salad, taco meat in pita bread, any leftovers from dinner the night before???