My left knee and foot hurt

Patient: Hi, I’m 20 yo female, I’ve never had an injury and I don’t practice any kind of sports.2 weeks ago I suddenly started having pain in my left knee when I walk, but it got better few days after, now the back of my foot is a bit swollen with a little pain, I can walk and move my leg fine but I’m wtill worried. Thanks !

Symptoms: Swollen, little to no pain