I have a soft painless lump on my bum near anus for 6 or 7 years. Its growing slowly. It is painless but it itches at times...

There are certainly. a number of possibilities for this finding. Unfortunately these cannot be evaluated over the internet. You will need to be examined. With this long of a duration it is unlikely but not impossible to be serious. Get it checked out now while you are young. Make an appointment for your health care provider to examine you.