Sorry to hear that you're feeling unwell. Intestinal distress can make you miserable.
Three comments spring to mind; firstly, that not eating in itself can raise BG - it doesn't in everyone, many people would simply fall lower over time, but I'm one of those that gets progressively higher if I go a while without eating. Your Iiver dumps glucose into your bloodstream if it thinks you're going hungry.
Secondly, a raise in BG can indicate an infection - likewise, your liver dumps glucose to fuel the fight against invading infectious cells etc. So your current illness could actually be an infection. IBS tends to be quite a long term complaint that you usually suffer with all of your life, I remember my first visit to the docs as a teenager with recurring bowel issues - at least 30 years ago.
Thirdly, have you recently changed your diet, or are you newly diagnosed and therefore modifying your diet to try and get BG down? I recently went to a lower carb routine when I started on insulin and did experience quite a lot of Intestinal discomfort as my body adjusted to the new foods. It's settling for me now, but I almost gave up, wondering if the new regime simply didn't suit me. Your body needs different enzymes and bacteria to digest different foods, so big changes in diet require your body to adapt and that takes a little while.
But, hopefully your doc will have covered all of these options as a diabetic I'm sure.
Not sure what to suggest in respect of eating without knowing what you usually eat. Safe bland foods are usually best when unwell, preferably things that won't raise your BG any higher.
