Hello there.... dont worry the fact that you mentioned you played badminton is actually a reassuring news as your knee and wrist pain could be a result of overuse and repetative stress injury...also do you remember twisting your knee or some external force or banging knee which might have twisted it little...coz morning stiffness and swelling could be a result of partially torn ligament or mensicus.... to be aptly sure bout it... in such conditions usually the blood tests apper in normal range.... Do let me know about your condition a bit in detail...it would help me in better diagnosing. Regards Take care