Ooooh! A spider bite, that could very well be it. When I was about 19 years old I woke up one morning, painfully & slowly got up out of bed, got my feet on the floor and then couldn't move another muscle, I was frozen in pain. I yelled/cried for my mom, who came in and helped me back down on the bed. I ended up having to be carried out to the car because I couldn't walk I was in so much pain, and when I got to the doctors, they discovered a spider bite by my elbow, it was big and swollen and nasty. I was put on anitbiotics, and it took a few days to recover. I hope that is what it is and you got that nasty infection our and he will back to his normal self!!!
Come on Zaners!!! (((HUGS)))