J.W.
1- Great cheese substitutes - Cheddar Style "Chreese" by Road's End Organics is great for making Mac n Cheese. That comes in packets. Also, we love Daiya Cheese which is found in the refrigerator section.
2 - There is good reason to avoid foods even if the allergy is not real bad. I got hives from some things, so I avoided those, but the allergy was not as obvious to others so I ate them in small amounts then ended up with eczema. It can also cause some subtle inflammation which can affect joints, brain, cause headaches, etc.
3 - One of my kids was like she was addicted to milk and cheese. And bread. She also could have lived off of milk products and loved loved loved mac and cheese. Wouldn't you know she had a really bad problem with Dairy and gluten. Life is ironic. btw - the problem did get worse as she got older until we found the problem and she avoids them now!