i just started lifting again after about a year off. when i got to my 3rd set of squats i couldn't bring the weight all the way down. i got to where my legs were parallel, but i felt a huge strain in my lower back, and it almost felt as if my back was going to give out. Therefore, i feel my lower back is in desperate need of attention. what workout should i be doing for my lower back? my work out is monday- bench/squat/row weighted hypers, and weighted situps, wednesday incline bench/squat/deadlift, pullups/situps; friday bench/squat/row barbell curls/tri extensions. what else can i work in to help strengthen my lower back?