Hi. Thanks for your query. Noted the history and understood the concerns. or one to say that you are suffering from IBS, it is necessary to have all negative investigations like that of blood, stool, CT scan of the abdomen, colonoscopy hence get all these tests done and if anything specific thing is found on the tests get it treated properly and a relief. If all the tests are normal then this may be IBS; C stands for constipation and D stand for diarrhea. It is possible that you have both in an alternating way. Tobacco in any form has a direct action on the intestines hence modulated the bowel habits well. Stress and anxiety have a major role to play hence should be under control and thus may need changes in lifestyle, job or any other factor that instigates or enhances the problems. There is also a role of foods and beverages, the preservatives that can enhance the problems and hence you should identify them and stop these altogether.