Haven't had a bowel movement in over 25 days what's wrong?

Constipation: There are a lot of different things that can cause this: medications like narcotics, metabolic problems like diabetes and hypothyroidism, problems with the colon itself like a blockage, or dead bowel, neuromuscular diseases like multiple sclerosis, stroke or parkinson's. This is by no means a complete list. Please see your doctor.

Long time: I am surprised you are not complaining of nausea and vomiting. You seem to be experiencing constipation. A bowel obstruction is a less likely expanation as your symptoms would be more urgent. Regardless of the cause, you should absolutely see a doctor about this. If you are not vomiting or in severe pain, your primary care doctor can probably take care of this.