How to erase something from your mind?

There's something that has happened to me recently were I thought I would be in trouble but everything turned out to be fine. Now I'm trying to forget what I did wrong because it is tormenting me. It's preventing me from being at peace. And its messing me up. I havent been eating as much, my stomach always feels funny, and I've been throwing up a little. It's got me so distraught that I've even been praying, and I'm not religous. How can I just forget this ever happened so I can be at peace again? Is there medication I can take? I hate feeling this way!