Dear Patient, IBS is a chronic digestive issue.. it will not go only with over the counter drugs. Kindly do not depend upon them . You need to see a good Ayurvedic physician in your area. My suggestion would be to contact someone passed out from Jamnagar University if it is close as they have good solutions.
Also to start with you can order sarveshwar rasayana of Ayurveda Rasayani Pune which I personally use in my practice for IBS . Also you can start with kutajghanavati tab 1-1-1 during diarrhoea and aragwadha choorna during constipation.
Next Steps
You need to take proper treatment from an expert as Ayurveda has good range of medications and solution for this problem.
Health Tips
Avoid eating junk food, curd, irregular meals, spicy food and non veg till you recover.