Hi with your short history this looks like you are suffering from Fissure in ano/ Piles. You need to go ahead with a short scopy done to rule out the same and depending upon the findings one can start medicine. You can consult a good surgical Gastroenterologist for same. Increase fibre in your diet , take plenty of water , salads in your meal as culprit for all bottom disease is generally a hard stool / constipation