Hello I appreciate your concern. Pain in lower abdomen and anal region warrants detailed evaluation to establish a diagnosis. I would advise you for a battery of investigation like Blood for CBC, liver function test, Blood sugar, an ultrasound abdomen and colonoscopy or proctoscopy for detailed check up. In my opinion you should book an appointment with gastroenterologist as per convenience for physical examination and above mentioned investigations. Don t worry about the periods, it might be related to pre menstruation syndrome. Meanwhile please follow these guidelines 1. Avoid constipation by taking laxatives like liquid paraffin or lactulose 30ml at bed time. 2. you should take lots of fresh fruits and vegetables with dietary fiber supplement in your diet. 3. You may require a course of antibiotics under medical supervision 4. In my opinion antiacidity medicine like pantoprazole or ranitidine group of drugs with antacids will definitely help you. 5. have lots of fluids in order to maintain good hydration. Hope you will find my answer informative and useful please feel free to ask for follow up question with relevant information and reports so that I will be able to tell you more precisely. Best wishes