I also injured my back Deadlifting 420lbs at 85kg BW for reps . . . . .I jerked a lift one day and was using wayyy too much lower back in general.
My pain was also in the lower center of my back.
It hurt everytime I deadlifted and put me off my training, hurt alot when I sat in a car seat for any length of time. . . . .So I went to see a Physiotherapist.
I actually went to an 'Osteopath' . . . He told me I had damaged my spinal erectors. They were in spasam . . . it was sore when he even touched that area of my back the first session
He 'worked' on my back over 2 sessions . . .sort of deep tissue massage and various other 'moves' to set my back . . that coupled with me taking a very close look at my form, backing off the weight and building more slowly has my back as good as new now. My back actually feels great now . . .
I would thoroughly recommend seeing a good physio/ Osteopath. He spotted a number of other imbalances in my movements too . . . .such as lumbar flexion in the squat, bad kyphosis in upper torso etc that I never knew I had. It was a good learning experience . . .
I found a certain Derek Poundstone video on Youtube excellent, in the way Derek explains how to actually use your lower back in the deadlift. . . .it just made so much sense to me the way he explains it . . . .simple but hugely effective.
Andy Bolton's book Deadlift Dynamite and Mark Rippetoes UTube Videos also helped me alot to fix a few flaws in my form and get back on track.
Im no expert . . .but thats my 2 cents if it can help all well and good.