Back Injury During Light Squats

Squat 1RM used to be 95KG’s performed in November.
Finally put squats back into my routine to see how it felt after a 2 month deadlift injury and now I hurt my lower back again only squatting 40KG.
During that 2 month period was mainly hitting machines for legs.
Some feedback on why this injury potentially occurred and what i can do would be appreciated…I will be going to see doc 2moz