Have you had any Antibiotics recently or any medication?
It could be anything causing the problem, and you might be wise to speak to your GP first in case it is a hormal issue, or some other medical condition.
If it is not some medical condition, then from the info you give on your diet, you seem to eat a lot of carbohydrates, it is possible that you have developed a yeast overgrowth. If you have taken any Antibiotics this can compound it. Yeast or Candida can cause a smell - google on the web and you will get plenty of info.
Even without the Antibiotics , if you develop a yeast overgrowth, then the balance of your intestines is out of alignment and you need to address that.
You should be able to get tested for a yeast overgrowth via a blood test, speak to your GP. If this is the problem you need to change your diet to an anti-candida diet, take probiotics, and depending on how bad the overgrowth is you made need anti-fungal drugs.
Another possibility is parasites.
You should read through various posts on this site and also see the Body Odor Support forum for additional info.