What Causes Severe Throbbing Sensation In Lower Back And Rise In BP Level?

Experiencing throbbing on both sides of my lower back that seems to be connected to my pulse. Feels as though the sensation becomes more intense and travels along each side of my back into my head again throbbing to my pulse. Not especially painful and in the past sometimes brought on by extreme nervousness. I have also been experiencing what I think is extreme spikes in my BP. I'm on medication but BP has been averaging over 180/100 reaching 225/124 at one point - at rest. Any idea what this might be?