Thank you for the query.
Its a long story you have given here so its gone be hard to answer all your questions. So if you could please point your questions out, it would be much easier to give precise answers.
Your symptoms sound like inflammation bowels disease. Most possible is Crohns disease
. This is what causes the inflammation. The factor is unknown. This diseases is an autoimmune disease
Due to inflammation process, your bowels gets narrow day by day. And as the bowels is build with muscle, it has an ability to become distended what makes first symptoms unnoticeable(the bowel can adapt to narrow area and work like there is no narrowing). However if the narrowing will reach some point where the intestine can not adapt any more, you get symptoms. Diarrhea
can appear as first with occasional stool obstruction, cramping, bloated abdomen. Pain is not necessary (distended bowels does not hurt at all).
After diarrhea, when the intestine gets so narrow that it hardly pass anything, constipation
To diagnose such inflammatory bowels disease, biopsy
is necessary (as the hole thing is visible under the microscope). This will allow to give best treatment.
So your next step is colonoscopy
Diarrhea very often gives urinary tract infection
so this is why you have pus cells as well.
Hope this will help. Feel free to ask further questions.