Ran into a similar issue with my 2018 back in October. We sought assistance with a PT group that works heavily with HS & College athletes. I paid the hourly fee for an assessment to find my son had tight hip flexors and IT band that were impeding him from activating his glutes. This put undue pressure on his lower back.
I agreed to pay for a few sessions to get my son properly stretched out and to show my son what specific moves he needs to consistently perform to get his glutes activating. Turns out this same PT group was know for teaching proper running technique as well, so it made sense to commit more time with this PT group.
Eight sessions later my son is now able to perform deadlifts properly and he is running with improved technique and speed. He's moving correctly and not in pain. It was well worth the investment.