I notice that when I put down the weight on my deadlifts to end a set the bar is always at a really bad angle instead of parallel in front of me. I also notice that when I'm done I have a sharp pain around my tailbone. This has always been when I have done deads on and off over the last 4 years. I have always maintained the arch in my back, but I fear that I may be leading myself down the road to injury if I put up more weight than I do now. (A pathetic 250lbs 5x6 at 155lbs bodyweight.)
So, question is, am i doing something wrong with my deads? Also, I do mostly compound movements, deads, squats, bench, cubans, dips and pullups. Do I really need any direct ab work? And could my lack of ab work and excess back work be causing the pain in my lower back all the time?