Posted by telnights
it sounds like either a bone-spur/chip or a busted blood vessel.
I thought about that initially, but I would expect his duration of pain and the fact that it comes and goes uncharacteristic of these things.
I had a bruised bone (which I thought might have been a chip at one point) on my knee from falling on a tile floor. It hurt like hell when pressure was put on it, but the pain was only immediate and went away as soon as the pressure was off. Also, the incidents of pain did not come and go, they only got progressively less severe over months (total of 3 or 4 months). I've also had spurs and they are similar to the above experience.
Rash or irritation is also something that doesn't sound like it is because I don't get why the pain would last for a long time afterwards. Again I have had lots of rashes and they are all brief acute pain.
Now, it could be also be an infection that is localized.
When you get a prognosis from the doc, let us know what it is. I for one am curious because it is a strange thing (IMO).