Maybe you are doing too much lifting through the week. I begin lifting @ 20 years old. I was lifting 4-6 days per week on a split routine (This was in the late 1970s). I was also working the oilfield as a pumper that required driving rough roads and lifting iron. I started getting some pain in my back. Not bad but a nagging slight pain that come and go. I thought I needed to stretch. I was into exercise too much to take time off. I ended up get to the point of having spasms and could hardly move, finally went to a chiropractor. Talk about humbling for a muscle head. I ended up having to take a year and a half off all exercise. I got fat and out of shape.
When I started lifting again I was doing a Mike Mentzer short HIT lifting and made better gains then the volumes of sets and rep I had done before. In my late 40's I cut back to lifting only once a week per body part and my bench press went to 365lbs. In my 20s and 30s my best was 305lbs. As Mark Sisson has said, it's surprising how little exercise you need to do to be fit. Dr Doug McGuff has come to the same opinion with his Body by Science.
Speaking from experience, do over do it and don't let yourself get suck into believing you need more then a couple workouts per week. That included distant running. Jeff Galloway, like Mark, was an Olympic marathoner running 20 miles per day. When he quite began doing seminars on marathon training. At one of his seminars was a guy who ran marathoners but only trained one day per week, because his job didn't allow for weekday running. He'd just do one long run on the weekend. He said he never hit the 20 mile wall in a race. Galloway changed how taught to running only 3 days per week.
I don't want you to make a similar mistake that I did by abusing your back and paying for it from now on. I'm 55 and mine still gives me problems to this day. Today I lift once per week, mostly on Cybex. I have to use the entire stack of plates on all the machines except wide grip pull downs and rows. The leg press is 390lbs and have to go up to 30-35 reps. I need more weight.
I sure you can tell, I'm trying to drive home a point. It looks to me that you are making a similar mistake I made are your age. With the exercise and your job you might be over doing it on your back.
Would I be putting a grain-feed cow on a fad diet if I took it out of the feedlot and put it on pasture eating the grass nature intended?