Was a special day yesterday, so we did something a bit different and got a 'large, luxury pizza' from the supermarket. Their own brand, have had in past and previously thought delicious when my own toppings are added.
Now, for over 6 months we completely quit processed food, just to see what happened. We actually really enjoyed making stuff from scratch (sauces, dressings, everything!) so kept with it. During that time we did lose a bit of weight as a consequence and my IBS calmed a lot. It's often triggered by stress though so never 100% sure.
So we had this pizza, it seemed innocent enough, the only things in it that we would not normally see in our diet were rapeseed oil, Wheat Flour [Wheat Flour, Calcium Carbonate, Iron, Niacin, Thiamin], acidity regulator (?), mozzarella, semolina and yeast
Within about 20 mins of eating it my gut felt like it turned to concrete and it was hard to bend, i felt sluggish and a bit achy for the rest of the evening. So did DP but in a lesser way. Certainly not unwell, but a marked difference to usual, as if digestive system was utterly insulted 
.
Today still a bit bloaty and stiff in the torso, like my soft tissue in this area is inflamed!
Nothing more to it, so din't think anything was down to allergy, but neither of us has eaten anything remotely like that for a long while. We had half each of 450g.
We always eat cheese, tomato, and the other toppings, so not sure it was that, but the thing was drenched in rapeseed oil as far as i can tell. Usually i use butter or extra virgin for cooking.
Could this be a reaction to the ingredients and this is how my gut always used to feel when eating processed stuff? Im quite surprised. But i havent eaten anything with wheat for so long now i guess i can't say.