re: Welp. Deadlifts got my back. Now what?

Salmon, I'd suggest getting a work up by a sports or exercise minded chiro or PT. The Supple Leopard book will have some common faults and mobility fixes for your (what sounds like) functional limitations.

Medical management for these types of conditions (if not surgical or injection warranted) is not typically best for active minded individuals. Pain killers and/or anti-inflammatories help in the short term but rarely are the long term fix. They do have natural pain and anti-inflammatory injections as well as dry needling, ART, & Graston technique which could be helpful.

You want to rule out anything major first though I do agree with a previous post. Having xrays, MRIs, etc in a full workup might be warranted depending on the history and exam.

It's also been my experience that people who are as active in a gym like yourself or others on this board benefit tremendously from having these types of physicians at their disposal for possible future acute injuries as well as maintenance and preventative care to limit these occurrences.

Hope you feel better soon