Thank you for the query.
Lack of apettite and constipation can be a symptom of serious large intestine disease. Especially if your mother is around 50. Blood in stool
, bloating, weight lost, fatigue can indicate colon cancer
. And this is the first thing which should be ruled out.
No acute infection lasts for years causing constipation. Chronic infection can do that, but stool tests are necessary to diagnose it.
Other possible reasons of such chronic constipation
are medicines (Ca-blockers, antidepresants), thyroid disease
, inflammatory bowels disease, IBS.
I suggest your mother to have some diagnostics. Blood work, abdominal ultrasound and colonoscopy
Hope this will help.