I should have added that, while I dont have access during the meetings, I do as soon as I leave them (same for him) so I would have seen before I even left work. He has my number since we've needed to coordinate by cell a few times for work and other stuff. I usually have a protein bar or two in my desk for emergencies so I could have grabbed one of those and gone to meet them at the right restaurant.  Someone else decided on the change of restaurant and it must have slipped his mind that I wasn't coming back to my desk.

But if you were not in the office and would not not have access to your phone, how could he inform you of the change in venue?

I thought there was, he's the one I told that I would not be back in the office or have access to my phone before the lunch. I've talked to him before about having celiac and he has experience with caring for food allergies. I think it was just an accident, it just didn't feel very good. Especially with no apologies for not telling me about the change despite being specifically invited. 

Read and understood with sympathy. Food for thought, excuse the pun. For future reference, is there an officemate you can count on to alert you when the group makes sudden changes in plans like that? Someone who is truly looking out for you?

What do you mean?