Dog agility and a knee injury

It took me three weeks to recover from the flu. In early March, I finally felt good enough to take my dog to our weekly agility training class. I had at that time, not started my own training. I had forgotten about the previous knee problems, was just happy to have enough energy to go out. I do compete with my Miniature Schnauzer in dog agility at hobby level. Each dog agility run is less than a minute long but sometimes involves quite vigorous running with sharp turns. Second training run with the dog broke my knee injury up again. I now realize that the dog agility has probably been the source of the knee problem all along. There are too much sideways movements. Back to square one. I started swimming and biking with no problems but had to avoid all running. It was difficult to even walk. My shape was way below what I could do last year. At the beginning of April, I started using an elliptical which seemed to help. I then increased the load on the legs to about 8 minutes run on a...