Did the same thing as you, Iron, except while doing good mornings. My back was collapsing with squats and DL and IIRC Ford told me to try GM's ala Westside's advice to concentrate on lower back strength. 1st one (ever, probably) I loaded up too much (132lb) and one rep was all it did. My back hurt for months afterwards, but being an ego-driven male I didn't rest or get a diagnosis. Now, I'm happy to say it's gone and my lower back is pretty schmick at the moment. My pain was a bit lower than you, probably 1/3 the way up my spine. It never really affected my lifts in terms of amount of weight, but it was an uncomfortable dull ache that made sitting/sleeping etc a pain in the ass.
Hope it recovers promptly. One problem I found was a lack of effective pain relieving stretches. All I could do was twists, which hurt, yoga-style squats, which were pretty ineffective, or lying on my back and curling up in a ball and rolling back and forth, which was the best but equally ineffective IMO.
"If trolling is an art then I am your yoda.if spelling counts, go elsewhere.........." - BL
"I don't do much cardio." - Ironfist
"Grip training is everything. I say this with CoC in hand." - abobo