Poor form can cause back pain in both the squat and the dl. Videotape yourself and post it here so we can critique, or better yet, spring for a session with a weight coach for feedback.
For your bench press, if you cannot complete your reps with good form, you cannot effectively move that weight. Do the same weight until all your sets are perfect, then move on. No need to rush, especially when you've already sorta hurt yourself with questionable form.
Big numbers don't mean squat if you're not performing the movement correctly. Nobody looks macho and tough in traction.