What Causes Intense Left-sided Pain Radiating From The Groin Throughout The Leg?

Hi! This is a 3rd day that I am experiencing a debilitating pain originating in my left groin and radiating all the way down the inside of my leg, all the way to my knee and even lower. I even have some occasional needle pricking sensation along the arch of my foot when this takes place. The first time it occurred at 3am... It kinda feels like an internal spasm or cramp, that intensifies and then gets kinda like dull ache...I am a 54 year old woman. I teach dance...but also sit a lot at the computer. Not really overly active, but active when I work. I can barely move when this pain strikes. Been drinking water and home-made electrolytes just in case I am deficient in potassium or something like that. The only thing so far that seems to help when this comes on is 3 Advils (over the counter). I am getting really concerned! This is so painful! What to do???