After many many years of false successes, I have now nailed my triggers.

Potatoes in any form, which sounds easy to avoid until you realise how many foods contain potato starch- which I now avoid and unspecified starch types on the ingredients list.

I find potato starch in pizzas, sweet potato fries, pastry products, corn snacks, grated cheese etc etc etc

I also avoid chocolate and coffee, but not caffeine in coke for example.

Hope this helps someone