Is Discomfort In Legs Causing Inability To Walk Sign Of Parkinson's?

My mom is 55 yrs old. She had undergone knee joint replacement operation before a year after suffering the pain for about 6 yrs. But now she complains of some uncomfortable sensation in her leg though it is not pain. She has difficulty in walking and feels difficulty in taking steps.She also has become very weak and tired and feels very sleepy. She dont report of tremors .My mom's two brothers have got Parkinson's disease in their 30's. Has my mom also got Parkionson ?