It continued for years and was fairly debilitating. I would get the sensation when running or when I was scared. It was a bit of a catch-22 because I would get scared of it happening, so the sensation would get stronger, and I would get more scared ...
If I was in a tight space, it would be worse. This was the sole reason I didn't go on roller-coasters or the like. Finally, when I was 19 or so, I stumbled upon a Wikipedia article detailing the "condition" and it's prevalence in other areas of the world. It was such a relief to know I wasn't the only person in the world to have experienced it; I honestly couldn't imagine anyone else experiencing it. I showed two of my brothers and we laughed about it. It felt good to tell someone else.
I don't experience it anymore.
Basically, if you have a small penis and gain weight (especially for already heavyset guys) everything around it grows while it doesn't get any bigger. This is otherwise known in the west via the not-unheard-of insult to overweight men: "You can't even see your own penis " In other words, they might imagine it shrinking into their body when their body is really just growing around it.