My nephew developed a swollen knee playing baseball. He just slide into home and the next day swollen. No outer skin abrasions. He ended up having knee surgery to drain fluid and remove infection. Cultures from the surgery came back negative growth. He was on oral antibiotics one week prior to surgery and now 2 weeks of IV antibiotics after. The problem is his sad rate and white blood cell rate briefly went down after surgery but no is going up sad rate 120 white count 15. I am worried.