Hi,I had gone through your query and understand your concern.
Before giving my opinion I need to know few more information like
stool mixed with blood and/or mucus,bad odour stool,quantity,number of purging etc.
From your history,amoebic dysentery
is a high possibility which needs to be treated with metronidazole/tinidazole
Since this is a prescription medicine, I would suggest you to meet the local doctor to confirm the diagnosis.
For your another query:Lack of enough fibre in the diet may cause constipation
Hope this answers your query.
Wish you good health.