At the time it read to me like your CNS was messed up. As in getting overtrained.
Out of curiousity (and since you mentioned a deadlift injury), how often did you use to deadlift? As in, how often during the week, and how many sets/reps, and how long did you rest between sets? Also, how many were your working sets and how many your warm-up sets and what percentage of your working weight was your warm-up weight?
I used to do very dumb workouts. I would do deadlifts twice a week. When I hurt my back, I was doing them on my back day 2x a week. Either 4 sets of 10 or 6 sets of 6, all work sets, with 1-2 minutes rest in between sets. I don't remember weights too well. I didn't warm up much back in those days.
Probably something like:
135 x 10 (warm up)
185 x 5 (warm up)
225 x 5 (warm up)
315 x 3 (warm up)
330-350ish for 4 x 10 (work sets)
If you think this sounds ridiculous, I used to bench press six days a week, do a hundred+ pullups every day, alternate jackknives / bicycles for ten minutes straight (easily the most grueling ab workout I've ever even heard of) etc.

I worked out like this for a couple of years and gradually entered the realm of sanity as I learned more and more from reading training articles / forums.
I didn't really know anything about form back then, so I doubt I was doing it properly. I remember my lower back hurt pretty chronically but I always thought "well i'll make a small adjustment and if it's not getting any worse, i'll just be careful and it will slowly get better." Then one day *POP*. Freaked me out, and I stopped then and there. Didn't come back to them for several years I think. I actually think there might have been another loud pop a couple days / weeks later, when I was doing lunges on a machine. I didn't think much of it at the time, and as the months passed I thought I had made a full recovery. I've read stories from people who said they heard loud pops which turned out to be herniated discs.
Now I worry that maybe this old injury is somehow still affecting me...
I've thought about the CNS theory, but I haven't lifted in 3 months and there's still no real improvement, judging from my experiments. "Adrenal fatigue" is something I've read a bit on as well, but i hesitate to consider such exotic explanations.