30M Brutal Lower Back Tightness after Hospital Cot

For the past 48 hours I've been sleeping on a hospital cot since my wife was delivering our child!

However, the cot was not very comfortable and seemed to have the area in the middle of the back protruding.

Upon waking up from a 2 hour nap - I had brutal lower-mid back tightness and could barely stand up

I tried stretching hamstrings and quads with no effect. What should I be focusing on? It seems middle of lower back right near the spine.