a month ago i worked up to what would have been a difficult five reps with 405 but on the first rep i felt a pop about two vertebraes right above the tailbone and got a fair bit of pain. i was able to complete the rep though. i thought it would take a few days to heal, but it took two weeks for me to be able to bend over in a somewhat natural looking manner w/o pain. i still feel and dull agravatting pain whilst sitting and flexion is the major source of pain. if i sit for a long time i will arch my back to ease discomfort(which is actualy a neat thing to remember).
i think the injury was caused by me not knowing how to warm up proper. i did it soon after waking up, starting with 295, and made it my first lift of the day. i did not want to do alot of sets warming up because my conditioning is terrible.
also my form might not be perfect, the area that got messed up is where i have been feeling the most pressure, i did tend to squat a bit to try to keep my back straight, maybe it did the opposite.
i want to start deadlifting again because that is my only good lift