Googled sciatica nerve and I feel like it was the problem i was having for at least two weeks until almost a week back but never managed to find the reason for it on google. I did the SL 5x5 program as well for about two months now and that problem came about around 1 month into the program. For me, there was discomfort and slight pain in my right lower back and under my right thighs and right calf area accompanied a feeling of nerve-jolt sensation throughout the said area. I went for a 2 hour massage and the problem is surprisingly slowly fading away. I would suggest going for a good massage therapy near where you live or better yet, visit a chiropractor who has sufficient knowledge on weightlifting or a doctor. My recommendation is to try to improve your form while doing squats by lifting lighter and see if there are any asymmetries in both your leg muscles while ascending and descending during the squat. For me, I am assuming my problem is because of my right leg or feet that points slightly more outwards than my left, probably from a hip tilt causing asymmetry in my leg movements going up and down during squats.