Both of those vegetables are high sulfur, and some people cannot take high sulfur vegetables/foods until they reduce their mercury load. You should test out other high sulfur foods like onions, garlic, cheese, etc and see if you have the same reaction.
In ayurveda certain body types do not do well with these vegetables, especially when raw. Also consider if you cannot tolerate brussel sprouts, cabbage, kale. An antidote is to either avoid them or cook them very well with a lot of oil or butter and spices.
These cruciferous vegetables are goitrogens (impede thyroid function)so there could also be a tie-in there.