Hi.
Thanks for the query.
Noted the history and understood the concerns.
Constipation for 4 days after a bout of diarrhea indicate that you might have taken
Loperamide or so. Also noted that you have been trying to sit on toilet but nothing comes out.
This may be due to fecolith
impaction.
I would advise you the following:
Get an X-ray of abdomen to see if there are fecoliths or
intestinal obstruction.
If there are no fluid-air levels of intestinal obstruction, start laxatives in the night and try with enema and/or Suppositories.
Continue with fruits and vegetables as they contain lots of fibers.
Also see for the foods and beverages that caused constipation in past and stop taking such things.
If hte problem persists you may have to visit a Doctor or at ER and get further assistance in clinical evaluation, examination and investigation to get an exact diagnosis so that an effective management can be doe. You may then need
colonoscopy and biopsy is something in the colon like cancer is suspected.