I have joint pain after 6 months of birth, it's getting worse. arthritis test was negative.what might it be ?

Discuss with MD: The hormone relaxin is secreted around the time of birth and may have a lingering effect. It is designed to naturally loosen the ligaments so your pelvis can accommodate the delivery. It often takes a while for the loose ligaments to catch back up but they almost always do. During the time of laxity the joints may feel extra stress.

Many possibilities: There are many forms of arthritis and you need to be seen and evaluated. There is likely little relation to your pregnancy as it occurred 6 months earlier despite the negative test you need to be evaluated by a rheumatologist.