Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain first thing is that if she had regular periods after unprotected intercourse then being worried about pregnancy is not needed as it is not the cause for constipation in her case.. Constipation can occur due to a number of common causes like sudden change in dietary habits, sedentary lifestyle that is lack of physical activity, hemorrhoids, Irritable bowel syndrome, lack of fibre in diet, low water intake,side effect of medication, hypothyroidism, weakening of muscles and nerves of digestive system etc.. I would suggest you to consult a Gastroenterologist and get evaluated and he can advise you investigations like colonoscopy, blood tests to check hormone levels, x rays, barium swallow etc to rule out the exact cause and treatment of underlying cause will relieve.. As of now she can take a high fibre diet that will increase the bulk of stool and ease in removal, take plenty of warm water, laxatives like milk of magnesia or castor oil can be taken.. She can take stool softeners like Docusate.. The doctor can also advise her prescription drugs like Lubiprostone or Liclotide.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.