I Have Soreness In My Left Knee That Started About

I have soreness in my left knee that started about 3 hours after a walk on a trail that borders a creek. The knee joint is swollen on the right side and it is somewhat difficult to walk. There is a knot on the right side of the knee cap. I am also experiencing some nausea and dizziness that started last night but not throwing up. I did see a small snake that looked to be running away from me while I was walking toward it. I didn't feel a bite and can'tontinued to walk another mile before going home and then these symptoms started!