While, it is good to avoid CT scans etc, the ones you have had may have increased the risk
for cancer. But a direct correlation is difficult to make. Also, just because you have repeated scans, it does not mean you will get cancer. Your symptoms can be due to several factors.
Chronic diarrhea can be due to parasitic infestations. Other causes are irritable bowel syndrome, celiac disease, Crohn’s disease, malabsorption syndromes, pancreatic diseases, diabetes, hyperthyroidism etc.