Low Back Recovery setback, but not entirely derailed from Easy Muscle prep

I woke up Sunday morning with low back soreness, as soon as I started getting out of bed. It was just like how my back felt every morning, during those first few days after my back injury this past August. The back felt tight and painful. The pain diminished as I started walking around.

I'm not a medical professional, so I can only speculate on possible causes:

• Back spasm during sleep, which apparently could happen
• Not enough hydration during the day and evening before going to sleep
• Somehow tossed and turned in bed, while sleeping, into a position awkward for the back
• Cumulative injury from training with the 24kg kettlebell before the low back had healed enough to tolerate the load
• Combination of the above

I did some yardwork, which involved some squatting down. My back held up fine. I later did a P3 mobility session.
Come Monday morning my low back was mostly pain free when I got up out of bed. I had a "mini spasm" accompanied with some pain, when I was sitting on the toilet. This scared the bejesus out of me but the pain quickly subsided after I was standing again and walked for a bit.

I practiced the Easy Muscle prep routine, as planned last week. The back felt fine until I did a set of goblet squats with the 24kg kettlebell. I did not feel a back spasm or acute pain, but there was just enough discomfort to make me reconsider the KB goblet squat. I quickly decided to replace it with assisted pistol squat, which felt much better.

I decided to work on pull ups (pronated palms) instead of chin ups (supinated palms). Last year I did partial chinups on the Eleviaa rings, which was ok because my shoulder did not let me drop all the way into a full dead hang. But now that I can work out of the dead hang again, I find the rings too low for my taste, even at the highest setting. To do pullups/chinups with these rings out of a dead hang, my knees and feet in front of my torso, which adds difficulty to the movement. For some scenarios this may be ok, but if the goal is to get in as much volume as possible in each session, you don't want to add unnecessary difficulty to the movement.

The DOMS in my lats from the first couple of sessions of Easy Muscle prep subsided. I've made steady progress in the P3 mobility method and continue to practice it on my recovery days. But I've gone back to stretching, instead of doing an abbreviated P3 session, for cooldown from my strength/hypertrophy training sessions.