Thanks for your query.
Noted the history and understood your concerns.
It is highly uncommon for a one and half year old boy to have recurrent diarrhea
unless there is contamination by a oral route as the child of this age starts putting in anything that is in contact with him.
Hence the cause of the recurrent diarrhea can be found out by proper observation and taking all the care that the child does not put in anything in mouth, particularly the ones that can be highly contaminated.
This give gastroenteritis
although recurrent viral attacks can such a problem and the results of stool tests are awaited.
I would advise you the following in such a situation:
Send the stool samples for tests for three consecutive days and a course of an antibiotic, metronidazole
and probiotics should help you child to have control over diarrhea.
You should feed him anything that is fresh, home-cooked and easily palatable considering the age.
Use boiled and cooled water and give multivitamins with zinc.