Running shorts have a draw string tie at the waist that does nothing if your shorts fit. I end up just tying it to keep it out of the way. I should have removed it. The knot of the tie was pressed firmly up against my stomach about 3 inches below my belly button. Yes...I have a high belly button. Anyway, this constant pressure on the knot was the culprit. The bump under my skin was like the knot you get from a hard bump. The only difference was that there was no bruise. I went to the doctor, just in case and that is all it was.
Lesson learned...pull out those draw strings!
Another lesson...smile at the finish line because your picture is being taken! All the shots of me crossing were rather serious.