Might be due to colitis. Which all antibiotics have you taken? For a start, you can take
1. High fiber diet. And
2. Probiotics like Tablet Vibact DS twice a day for 5 days.
Next Steps
Consult expert near you. Go for Ultrasonography of Abdomen and pelvis. And stool for routine microscopy test. In long term cases to rule out other causes, you might need colonoscopy but ill advise you to visit nearby surgeon first.
Health Tips
Not to use too much of antibiotics without knowing the cause of colitis.