What Causes Swelling And Pain In Knee Joint?

My son is of 16 years old. At right knee of his leg on 01/11/10 swelling started with pain. After giving him anti biotics injections after 20 days his swelling came down to 90%. But still pain is there. He could not walk freely due to pain. Every evening his tempreture gets rised upto 103-105. He avoid to eat and got 8 kg weight loss. Blood test reports shows Haemoglobin 8.1 L, RBC - 2.83 L, Total WBC count- 16400 H, ESR value is 140 H. Can we conclude that it is bone TB ? No biopsy has been done. However Dr. is of the opinion that its Bone TB. Please Help.