Strange knee / quad pain?

pkripper
pkripper Posts: 652
on saturday, went for a ride, same bike as always, so set-up not changed and all was fine for about half an hour. Then I got a gradual onset of knee pain, which over the next 15 minutes got to the point of needing to abandon the ride. It was a flat ride, so nothing that hills could exacerbate.

The pain is directly at the end of the inside quad muscle and only manifests on the downstroke, and definitely more muscular than anything else I think. It was fine for a run immediately afterwards, but hurt again this morning when I tried to commute in. It's not consistent in intensity at all. It almost feels like a nerve being tweaked - and it's too far away from the kneecap to be related to that I would have thought.

Any ideas what it might be? The only possible cause I can think of is a change of shoes for saturdays ride, but the cleat position should be virtually identical, as they're the same brand of shoe, in the same plane, and I've used them interchangeably up until about beginning of may - all other set-up is the same.