Hello and hope you are doing well.
It could indicate a food allergy. As repeated episodes have occurred with consumption of the same food. Allergic reactions are mediated by IgE antibodies, which are released on exposure to a particular allergen. These in turn activate mast cells and lead to a local response or systemic anaphylaxis. It can occur at anytime. It may help to maintain a food dairy and keep monitoring your symptoms. This will help to narrow the search and avoid them. Further allergic testing may be worth looking into. Here an allergy specialist may confirm the allergic reaction and can further help to desensitize you.
Hope this helped and do keep us posted
Thanks! At the moment I've just stopped drinking Vimto and everythings normal stool wise, nothing else seems to have bought it on. Just seems really weird because I'd have thought it would be one ingredient I'm allergic to which would be in other things?