Thanks for your query.
Noted the history and understood your concerns.
from overseas that turned out to be recurrent and blood diarrhea can be treated with Metronidazole
and acts as drug of choice for travellers' diarrhea.
If the stool samples show an active bacterial infection an added antibiotic like Ofloxacin
or Cefixime can control this better.
Also needed is probiotic
Take banana, curd/yogurt and activated charcoal tablets for early and better recovery.
Use only boiled and cooled water.
Consume only fresh homemade foods.
Complete the courses and avoid the exposure to infection through oral route so that there is no recurrence.
If the problem persists even after a proper treatment then you may need the tests of blood and colonoscopy
and biopsy to get a proper diagnosis and get further management as per the cause found.