Pain from the past has a habit of hanging around or showing up unannounced. It will rain on your sunny days and trample on your happiness. The only way to move on is to address the pain and let it go.
You can try to avoid it, but it won't leave you alone. You can try to ignore it, but it will continue to show up consistently until you address it. What caused you this pain? What were you meant to learn? Why can't you let it go?
Get to the heart of the matter. Sit down with it, rummage through it, sort it out, so you can release it. When you set pain free, it will cease to have power over you.
Don't be a servant to the past, not when there is so much to experience in the present. Let go of the pain, so that you can get on with the business of living a vibrant, healthy, happy life.