Reaction straight after eating or would it be delayed?

[Ouchhh]

Hey,

Does anyone know if a food intolerance would present with diarrhoea straight after eating the food you're intolerant to or would it be from something that you ate the day before ?

For example if on Monday I ate Spag Bol for evening meal and then on Tuesday I had milk and cereal for breakfast and a ham sandwich for lunch followed by urgency/stomach cramp/ diarrhoea would that be because of the food I had that day or the day before? Or would it even be from the Sunday ?

I'm so confused and frustrated with ongoing tummy issues 4 months postpartum. Trying to pinpoint what the issue is as when I eat bland (I'm talking rice, potatoes, meat , veg and fruit- it's fine but very soulless and it's making me miserable eating like this everyday) I don't get these issues but it's so hard to work out what food is the culprit.

I did an elimination diet for a bit and thought I'd figured out it was gluten after a seemingly bad reaction to a croissant but I've had some bad episodes straight after eating gf fajitas and soup with some cheese which are both gf so now I'm not so sure.

Had bloods , stool & pelvic and tummy ultrasound test but nothing majorly significant from these.

Can't get a colonoscopy right now due to birth injury but I am going to ask about the gastric camera they can do...

Any ideas /thoughts/experiences welcome 🙏

My reaction is about 8 hours later, but if very small, microscopic, amounts of gluten regularly, it can be a cumulative effect.
i think if I had the equivalent of half a slice of bread I would vomit

Non-ige allergic reactions can be anything from immediate to 72 hours later. The only way to diagnose is to eliminate the food entirely for about 6 weeks, see if symptoms go and if they do eat the food again (challenge the allergy) and see if symptoms return.

I have non-Ige reaction to Dairy sometimes I can tell straightaway and get stomach ache, other times it's definitely more delayed.