Is smelling like poop and pain at the bottom of the anus, common symptoms of a fissure fistula

Anal fistuka. Your symptoms are certainly worrisome for an anal fistula. A fissure presents as painful bleeding. A fistula presents with external pain, drainage with a foul odor, and generally involves a previous anal procedure, but not always. Consult a surgeon, as surgery is effective treatment for both.
Pain. The primary symptom of an anal fissure or fistula is marked anal pain, worse with bowel movements, sometimes rectal bleeding. Need to see a doctor for an exam.