What do your intolerances manifest as?

Hoping someone can help. I've had the most ridiculous year, first thinking I might have labyrinthitis and then 'silent migraines'. Turns out if I eat very carefully (avoiding carbs except rice) I'm ok. However if I do I can become dizzy nauseous and disoriented. And I get a ghastly hangover from some stuff. Well it feels like that. Anyone else out there been here? Doctors think it's not normal. Anyone been down this road already? Have never had any food issues before. Am 36, pretty fit cyclist till this came up, if a bit on the chunky side.