Reactive arthritis is an rare joint disorder mainly occurs in knees ankle small joints
It's due to reaction to bacterial infection
Mainly Chlamydia and next salmonella shigella etc
If you have severe pain lasting for weeks and months,you have not benefited from the early treatment,then the doctor is right asking for these tests
Next Steps
usually it lasts for months with on and off flare-up
proper diagnosis and treatment is suggested