What Causes Numbness In Arms And Legs?

I am a 34 year old female with no significant health trouble. About 3 months ago I notice that my left arm and hand gets numb when I am in the bathtub. I also notice it sometimes going to sleep or waking in the am. I use one pillow and have no neck pain. I went to the ER 2 weeks ago with a chest pain and because of the arm thing and my family history, they admitted me. All checked out ok and was told to follow up with neuro. Any clues what this could be. I do have the thing when your fingers turn white with a touch of cold. Vericose veins, non smoker. thanks