What Causes Burning Sensation In Rectum And Blood In Stools?

I am 36 years 2 years back one hemroid was removed by using knot my stool is passing normally. It is three to four months back to till when passing stool i feels burning sensation some times in my rectum with a minute amount of blood at last. when burning occurs i having a tendency to pass stool more times and the stool looks semisolid type ( I go to toilet every day two to three times). But today i gone toilet two times in morning and feel burning sensation mildly. After my lunch I gone toilet one more then the first stool comes with one side is mixed or like pasted tomato ketchup like blood please answer about this I am very nervous.