Try some trigger point releases on the particular muscle thats giving you issues. I'm having to switch my ultra wide stance squatting technique to more of a closer stance since I tweaked my hip last week. Deadlifting didn't effect the psoas much, but I know squatting will. So tomorrow will be working on the new form without much weight.

Good luck on the recovery and put heat on it and stretch!

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Quote Originally Posted by JM1000 View Post
lower back pain on the right side each and every time I try deadlifting and/or other posterior chain movements...

Stretching hips for a while helps a little but wont do it... can't even tell you what happened, one day it was just like that. The week before I was setting PR's and the next week bam! form was decent so i'm pretty sure it's not a bad movement issue
Maybe your lower posterior chain and core isn't strong enough... Or maybe you're not engaging your core enough and its putting tons of strain on the lower back during the pulling.