If a patient with theses symptoms: abdominal cramps in the upper and middle third of the abdomen, not anemic, not diabetic, no bloating, no mass seen upon ultrasonography, no loss of appetite, and no fever. The patient experienced a food poisoning with mild symptoms for a weak and had abdominal pain only after a meal ,but now he is suffering from a pain and discomfort that are almost persistent and not related to a meal. After ultrasound has been performed for the kidney and urinary system, 2 simple kidney cysts and bilateral kidney stones were shown. CBC wasn't significant except for elevated basophils and as far as I know, elevation in basophils indicates recovery from infection. Patient is 51 years old. Urine analysis shows, erythrocytes and this is patient always exhibit blood in the urine due to other urinary problems. Stool analysis was normal and no blood was detected. Upon percussion on abdomen, nothing appear to be significant.
What's your diagnosis?
Could it be post-infectous IBS, ulcerative colitis, colorectal cancer or other cancerous lesions related to the GIT?
Should the patient has another stool analysis tests to confirm the diagnosis?

Thank you in advance.