What Causes Severe Intermittent Itching On Legs?

My name is Nina and for the past several years I have been experiencing itching on my legs starting at my ankles and moving up to my thighs. It comes and goes and feels like it is coming from the inside out and no matter how hard a scratch there is no relief. It feels like what my mother use to describe her "hot flashes" felt like but without the sweating, just itching. I take several supplements including primrose oil, omega 3 and a multivitamin for woman 50+. I do not have dry skin or suffer from any skin condition, nor do I have any rashes. I exercise daily and eat healthy. My doctor has run blood test and everything has come back normal and I have been sent to a specialist who says everything is normal. Can you help?