I had this recently and also left it a few years as i was embarrased. i went to the doc and yes she had to have a quick look, nothing major tho, and it was an anal fissure, a small tear in the skin. this causes great pain when passing poo, like glass being pooed out!, and also fresh blood on the toilet paper. whereas i think cancerous blood is more in the poo itslef.
a simple cream did the trick, i find it comes back when i eat rubbish.
make him go and let us know wot it was