My father, 91, 165lbs, 5'5", has had several falls over the past 6 months. Fortunately, no serious injury 4, but he says that he feels like a "wave" comes over him and that his legs shake and he feels weak. Then he falls. Is this an emotional reaction or could there be more to it? He takes medication for high blood pressure, depression (since my mother passed away 4 years ago) and gout.