What Causes Fever With Knee Joint Pain?

Good evening. Sir i have been getting fever with knee joint pain since the last 10-12 days. As advised by the family Physician i got myself investigated for blood investigations such as MP, Widal, Dengue and Chikungunia. All these tests have come negative. The fever subsides till the time i m taking the medicines prescribed by the Physician. The moment i stop the medicines the fever is back with the joint pain. Please advice.