I was working in Denmark on a farm but took 5 days off to see the Euro96 soccer tournament in England. On the way back I took an overnight bus from London to Amsterdam and then hitchhiked all the way to Denmark in one very long day. The next day I was exhausted and had a bad sore throat. A couple of days later my knee was the size of a soccer ball. A doctor claimed that an infection traveled from my throat to my knee.
I had to have an operation. (They wouldn't let anyone take photos in the operating room, so I only have this photo--deepest apologies.) They extracted a lot of fluid, but they lost the sample before they could test it. They asked for me to have another operation to extract more fluid, but I wouldn't let them. I eventually recovered, but I never knew what the problem was.
They were embarrassed so they didn't charge me for the operation. It's a very long story, but I ended up getting money through a claim with the State of California's Unclaimed Property system. Worthwhile to check out if you have ever stayed in California for a while.