It's very obviously a cycling related injury but the only information I can find either in books or on-line says it's an overuse injury and to just rest it. I can only describe the pain as severe, there's a dull ache when resting but when riding (or even walking) the pain increases to the point where any sensible person would stop

My bike set-up hasn't changed in any way and the problem started on the 3rd consecutive day of (fairly intensive) riding. I know I should have stopped at that point but didn't have much choice but to continue for another 100km or so, which obviously hasn't helped the situation :?
I haven't thrown a leg over a bike for the last 3 days, I've tried to limit walking, etc and while it's less severe it still hurts like hell ...imagine riding with a dislocated knee and you'll get the picture.
Thoughts, suggestions most welcome.