Yash,
I don't know much about E-Coli but IBD(inflamatory Bowel disease) includes Ulcerative Colitis and Crohn's disease. They are very similar conditions but in UC inflamation is limited to colon only while in Crohns, it can be anywhere from mouth to recturm. Another major difference in how it looks during colonoscopy. For UC inflamation is continuous and superficial and for Crohns it is patchy and deep,doctor sees normal area between inflammed areas.
Since you said that you have inflamation in small intenstine too so is it possible that you have crohns and not UC? I don't want to assume as inflamation can be for different reasons but check with your GI. Call him and ask few questions 1. Where exactly you have inflamation in small intenstine? 2. Is your inflamation is continuous or patchy? 3. Does he think inflamation is due to E-Coli or is it Crohns?
What tests did you have? If you had colonoscopy, did he take biopsies? Biopsies help identify UC vs Crohns.
What ever it is,initial treatment is same. Main difference is if you ever need surgery. If you have UC, after surgery its gone but crohns normally comes back.
Hope this helps.Read as much as possible and go with lots of questions to your doctor.