who only by moving can balance

Yep. Except a physio told me last week many people have it, and it has a name I can't remember, and its fine and normal unless its accompanied with pain, or particularly loud/bang/crack. For my shoulder, where it happens most often with pain, its cartilage moving across/against bone and tendon. Noise/sensation can also be made by bone and tendon and sensation of fluid moving inside joint is result of pressure being released and blood rushing to area