Thank you for the query.White spots
in the stool can be undigested parts of foods or fungi for example.
It can appear due to constipation
. But you should be rather worried about your constipation.
You need to know that over the age of 50 the risk of colon cancer
significantly rises. Constipation can be one of the colon cancer symptom. Moreover, constipation can cause large intestine changes.
That is why every person over the age of 50 should have colonoscopy
every 10 years.
Other possible reasons of constipation are chronic bowels infection, bad diet, medicines (Ca-blockers, antidepressants), hypothyroidism
I suggest you to visit your doctor and consider this possibilities.
Hope this will help.