that is just a small umbilical hernia, so small that you should only observe it and if you go to a doctor with it, you will lose only time and money.

u hv 2 muscles there side by side in your abdomen; the rectus abdominis,(look at those six-packs); if they separated, you get divarication of rectus abdominis.. gives you hernia too; now in this case exercise woulda strengthened them muscles around the area. what u hv here may not involve those muscles, just a weakness at where the umbilical cord was, made more prominent in your case maybe due to new weight gain or new bouts of coughs.

yeah, may well be psychological.

mind you, that umbilical hernia could get bigger if gain weight or lose muscle bulk eg in protein malnourishment etc