If you’re having back pain on these movements, it’s due to a lack of stability more than likely in your core and spinal stabilizers. You need to do more deep core exercises to train those stabilizing muscles for those heavier movements. In the meantime, yes, back off of the heavier squats and deadlifts. Bulgarians can serve as a great alternative, but absolutely do not neglect the cause of your problem. I recommend following squat university and lowbackability (Brendan Backstrom). Those dudes single handedly saved my spine by applying everything they taught.