Probably a gluten free trial for both your daughter and your hubby would be best. If you're the cook, you DON'T have to necessarily tell him that the food is gluten free (I've learned to make absolutely anything gluten free, and people cannot tell the difference), but of course, he could always screw it up by eating out for lunch.
A gluten free trial could be as simple as feeding everyone gluten free food for a week, then re-introducing gluten and finding out if anyone feels sick (diarrhea, constipation, bloating, headaches, abdominal cramping, vertigo, etc, etc.).
If you do go gluten free, there are a few steps you need to take in your kitchen to eliminate cross-contamination. Please read the following blog post for great tips and info on how to go gluten free:http://glutenfreegoddess.blogspot.com/2006/01/morning-after-diagnosis-that-is.html
Here are a few links to gluten free recipes:http://crockpot365.blogspot.com/http://glutenfreegoddess.blogspot.com/http://joannsgfrecipes.blogspot.com/
A genetics test would be recommended for you, your husband, and your other children since your daughter may have celiac.
Your husband needs to understand that celiac disease is a very serious illness that can cause an incredible amount of damage. Not just to the intestines, but it can actually
open the door for all sorts of other autoimmune diseases to develop later in life. Just count the number of AI disease in my signature line!!!
Please read the following article to your husband:http://www.umm.edu/news/releases/zonulin.htm
Celiac disease can also cause neurological symptoms and permanent brain damage; people with untreated celiac disease have a much higher risk of developing certain cancers. There are a number of medical journal articles on many of the different problems associated with celiac disease (autoimmune thyroid disease, liver disease, RA, even lupus).
Good luck to you!!