What do I tell the nice people who made me dinner?

After a good year of struggling not eating anything with lactose or gluten in it, I feel fairly confident in the brands I choose, the meals I make and the amazing flourless dark chocolate cake I bake.  Then, you throw me into someone else's world of cooking and it's like - "Sorry, I can't eat that, even though you've just spent a fortune on it" or "Sorry, I can't eat that even though I know it took you two hours to make."  Then, I feel really bad, because they don't know - it's not like I wear a sign that says "please don't add butter or flour to that."  Maybe I should bedazzle a shirt that says that to avoid these awkward conversations.  How do you avoid this?  Well, today, I don't have the answer.  I'm still working through this.

"I'm allergic to wheat and lactose." Oh, yes, this will totally explain to the nice family making dinner for you that you cannot eat scalloped potatoes and ham.  NOT!  They're going to look at you like you're one of those people who should live in a bubble because you're allergic to everything.  So, what next - try to get around it without telling anyone or asking any questions - so when you're in the bathroom later crying in pain... you're right, that's a great solution.  Next!?!?!