I've never experienced "back pumps", but I've been using Epistane for about 3 wks now & over the last 5-6 days I've been having some crippling lower back pain! And I do mean crippling, to the point where it's limiting my range of motion, I can't sit or lie down in one position for too long, it wakes me up from sleep, and even with taking 6 aleve and 3 tylenols a day I get hardly any relief!!! It feels like severe pressure/tightness, with waves a spasms around the lower back-waist, basically the sacrum area. I can't recall hurting myself while lifting or at work. It just came on suddenly a few days ago. Could this be related to the Epistane? Anyone else experience this while on Epistane?