Suggest Remedy For Inability To Balance And Stiffness In Legs

i have problem that when i climb upstairs or down stairs i feel that i cant
balance my legs and feel stiffness in legs muscles and fear that i will fell
down.. I had medically tested all the tests that is absolutely clear from all
aspects but this complaint is still there. Kindly give some advice that why is
it so? And how it can be treated???