Thank you for your query.
Was a stool examination ordered? If not it is advisable to get a stool examination done to know the cause of frequency of motion which is not responding to the medicines being given.
Another alternative could be to tweak the medicine being given. Instead of giving a combination formulation continue with only metronidazole
for a total of 5 days and add lactobacillus
preparation to change the bacterial flora of the intestines.
I hope I have answered your query to your satisfaction. Do feel free to revert back in case some clarification is required.
Wishing your son a speedy recovery.