Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
can occur due to a number of causes like sudden change in dietary habits, excess intake of dairy, taking a low fibre diet, lack of physical activity, stress, hypothyroidism
, irritable bowl syndrome, eating disorders etc. However in your case it is due to medication causing the side effects, it will get better gradually. Feeling of a knot is due to lack of bowel movement. I would suggest you to consult an emergency room and get checked. You can be advised to take high fibre diet, do moderate workout, take walk after meals, drink plenty of water, take laxatives and stool softeners like Docusate, fibre supplements
like Psyllium. You should eat after every 2 hours. Go to toilet on the same time every morning and try to evacuate your bowels as it can help in developing habit of regular bowels. You can be advised prescription drugs like Lubiprostone
Hope I have answered your query. Let me know if I can assist you further.
Dr. Honey Arora