I have had this happen on past Whole30s, but usually much earlier. I am on R7 Day 20. Today and yesterday, at the same time in the afternoon, I got super nauseous.
Yesterday, I ate:
Peas and a hamburger
Riced cauliflower
Italian sausage
Red pepper
Cassava flour tortilla
Carrot
Cilantro
Lime
Today I ate (before the stomach upset):
A little bit of chia seed pudding with raspberries
A russet potato with ghee and peas
A dried mango strip
Tuna, kale, avocado, tomato for lunch
Apple with coconut butter and cinna