Most peanut butters have an oil added, sunflower, safflower, canola, vegetable, corn...you might have an issue with any of these oils or be reacting to CC from the oil. (I'm trying my best to have a CC free diet, and so I'm avoiding all oils that I suspect might have other grains in them, which leaves me with animal fats, olive oil and coconut oil.) Try a natural peanut butter that isn't emulsified with another oil. Nuts to You Butter Inc. brand I *seem* fine with. Only downside is that they need stirring before you use them, as the peanut's natural oils separate over time from the rest of the peanut.
To note, I didn't seem to do well with Barbour's peanut butter even though they claim it's gluten free.