Hello
I appreciate your concern
Looking at your detailed history you might be having fissure or fistula in anus and chronic UTI
Your doubt is genuine Black and red particles in stool could be occult blood
In my opinion you should consult your doctor for per
rectal examination and a battery of investigations like blood for
hemoglobin, CBC liver function test,
stool test and urine culture and sensitivity test
You may require a course of antibiotics under supervision of your doctor
Meanwhile please follow these guidelines
Have plenty of dietary fibers fresh fruits and vegetables
Have lots of fluids like fruit juices and ORS solutions
Avoid
smoking and alcohol
sitz bath will definitely help you
Avoid
constipation by taking stool softening agent like liquid paraffin
Hope this answers your question
let me know if you have nay doubts, I will gladly answer you
Best wishes