Hi,
MS can cause hip and knee pain due to muscle spasticity and weakness. However it is important to rule out other causes also like arthritis, osteoporosis, osteomalacia and spinal stenosis as they can all present as hip and knee pain.
Please discuss these possibilities with your treating doctor as it is only after a careful clinical exam that a diagnosis can be made with certainty.
i am having left hip pain which goes down the back of my thigh and leg. went to the doctor and learned that the pain was coming from my lower back. the muscle runs from the lower back to the buttock muscle which that muscle goes to the hip and that what makes it goes down the leg. (sciatic nerve pain). google it and you will find information about it and exercises you can do to help. hope this helps