What Causes Sudden Tailbone Pain A Week After Lumbar Puncture?

I had a lumbar puncture a week ago and thought I was slowly healing up, though had some tailbone pain radiating down the back of both legs. However, yesterday, 6 days after the procedure, the tailbone pain suddenly became unbearable. When I go from a sitting or laying down position to standing, there is a rush of pain that rushes down to my tailbone and then radiates down the back of both legs. This rush of pain is crippling - knees buckle, have to hold on to wall, makes me cry out type of pain. Why would this come on 6 days afterwards and what could this be? I am female, 5'2" and about 130 lbs. I didn't have headache after the l.p. I can also feel the tailbone pain start if I am laying down and start to pick my head up, and it also happens if I am standing but turn my head to the side - my tailbone feels that rush of pain. And then starting last night, the tailbone also had throbbing pain (different from the rush of pain) that kept me awake.