Food allergies; not sure where to start.

Yesterday I was at the grocery store with Bob (they didn't nap at the same time and Freddy was home napping w/DH), and we ran into the educator from the county who has been working with Bob on speech development and behavior issues. She started chatting with me and expressed concern that he might have food allergies, that she felt sometimes kids with food allergies didn't feel well and that caused them to act out.

This wasn't a big surprise to me. I've mentioned Bob's problems with serious and chronic diaper rash that seems to be yeast infection most of the time. And I know that discomfort from the rash has contributed to some of his bad behavior. What has kept me from acting more on it has been my uncertainty how well we'll be able to implement any food restrictions or even practice an elimination diet if asked. Their nanny and I figured out that highly acidic foods like the mandarin oranges we used to give them and tomato sauce causes him problems. Yeast implies too much sugar to me, and right now they are eating more sugar than I'd like, but he's had this problem when we had their sugar consumption more under control, and his rashes currently aren't worse than before.

I'm having enough trouble keeping them on a semi-healthy diet as it is, and I don't know how I'd manage a special diet at day care. The most difficult part, though, would be his twin brother. Bob is in the 95th percentile for weight, while Fred is in the 10th percentile, and I'm very reluctant to impose any kind of restrictions that may inadvertently lead to Freddy getting fewer calories. And I'm concerned about how cooperative DH might be, too, especially if he's skeptical about food allergy as the source of his issues.

If you've dealt with food allergy (and, please, at this point I'm only focusing on allergy, not food additives or preservatives), especially if you have twins:

*Did you initially work with your general pediatrician or go directly to a specialist for help?

*How did you manage diet if your child was at day care?

Any ideas in general?

Many thanks,

Maggie (in VA)