I have muscle spasm at left side of lower back from doing deadlifts what to do?

Plan is: Decrease weight higher reps/ lower weight heating pad at night stretching nsaid's massage see doc/pt if persists and definitely if it worsens and has nerve symptoms.

As: We age, our disc spaces narrow and flatten, our muscle loose elasticity and don't heal as well. Stretching and warm up is important to avoid injury. Once injured, you need to rest, take an anti-inflammatory and or muscle relaxant. Consider different exercises in the future.