What type of nuts are you eating and maybe the quantity?
I can eat almonds, hazelnuts, pecans and walnuts in any amount without experiencing any problems. As for Brazil nuts if I eat more than three at a time I do get that stone in the stomach feeling.
I found out that cashews are not a good idea as they are very high in carbs. I rarely eat peanuts as I found out many years ago that I have a sensitivity to them. Peanut butter is fine for some reason (no sugar added of course). Of course both peanuts and cashews aren't really nuts but everyone lumps them into the nut category.