He has been tested for basic allergies, not specific food allergies. I've not noticed a "brain fog" but I will pay closer attention. The foods that he was able to eat but now cannot are: biscuits & gravy (southern style), chocolate cake (but chocolate icing, ice cream, or candy is fine), hibachi style Japanese food, Thai food, bacon (unless it's crunchy/almost burnt), canola oil, olive oil, butter (not margerine), I think that's about it.