Thank you for the query.
Lots of banana intake is know to cause tiny black spots in the stool. This is quite common, so most likely worms are not your problem.
However diarrhea, lower abdominal pain
at the age over 50 can indicate colon cancer
. This should be ruled out at first. To do that colonoscopy
needs to be done.
Lower abdominal pain could be also caused by diverticulitis
. This disease is caused by chronic constipation
. To diagnose it, also colonoscopy needs to be done.
Bacterial infection or parasites are also possible. That is why if colonoscopy will be negative, stool tests needs to be done.
Hope this will help.