My knee has really gone wonky today, it was sore yesterday, this morning it was still sore, later today there was a very loud snapping sound and I was in agony, pain from the knee right into my foot. It has eased a little with pain killers but can't walk without pain. Luckily my Dr has one appointment left in the morning, so will see him then. The joint still seem stable so perhaps it is ligament or tendon based. I jarred the knee last week when I caught my foot on something whilst walking, it became swollen, but with rest & ice, improved quite quickly.
Just hope this is a temporary setback, was getting on so well.