What Causes Painless Bump Under My Penis?

I have a small raised spot (mole?) on the underside of my penis, near the glans, that causes my wife extreme pain when we have sexual relations. It's having a negative effect on our intimacy and it's been months since we've made love because of the pain it causes her. She said it feels like a knife. What can I do? This has only been happening the past 6 months or so (we've been married over 35 years). Any ideas?