It's not uncommon for a patient with neurofiberoma to experience weak legs and involuntary movements; it's common for a lump of feet and neck to run some tests to make sure that they're actually nerve fibrosis.
Doctor, you've lost your leg, you've got an abnormal inert movement, you've got a lump in your foot, you've got an abnormal skin, you've got a lump in your neck, what's the problem?