HI, thanks for using healthcare magic
It would be best for you to be seen by your doctor for assessment especially with the blood in your stool unless you had a recent (within last 2 years),
colonoscopy.
Nausea can occur with migraines, it is one of the commonly associated features.
It is not usually associated with an odor in the nasal passages, this more commonly occurs with infections of the nose or
sinuses.
Your assessment by your doctor should include, a history of all of your symptoms, examination and investigations.
You may need prophylactic migraine medications- this is medication to reduce the number of migraine
headaches that occur
Depending on the last time you would have been scoped , a look into the intestines may be needed as well.
If the sinuses are infected, antibiotics would be needed
I hope this helps