Hello! Thank you for the query. If you have been taking antibiotics after the surgery, this could cause your symptoms. Due to antibiotics use, natural intestine bacteria get killed so the bad bacteria can grow. This can cause symptoms mentioned by you. Other reasons of constipation are medicines (ca-blockers, antidepressants), thyroid diseases, bad diet (low fiber intake, low mineral water intake), inflammatory bowels disease or even colon cancer. If you are over the age of 50, colon cancer should be ruled out at first. It is quite characteristic to have diarrhea and constipation alternately with colon cancer. Other possible symptoms are weight loss, abdominal pains, low hemoglobin level, weakness, blood in stool. In such case colonoscopy should be done at first. If you are younger than 50, you should start with stool tests and stool culture test should be done. Please discuss with your doctor Rifaximine treatment for an infection. Hope this will help. Regards.