Today, as I was working out, I decided to go ahead and do a couple of sets of barbell back squats. I was using pretty light weight but after the 3rd set or so, I was feeling some pain in my lower back that made me stop. I'm not sure if this was an injury or just my lower back was fatigued from doing rows the day prior. So I decided to switch to doing barbell front squats, under the hope that it was easier on my back. I am pretty new to front squats, and it seems that every single time I do them (I do them bodybuilding style, with my arms crossed over the bar), my right shoulder seems to hurt.
My question is, how do I know if my lower back pain is from an injury or just from muscle fatigue? I currently don't feel any pain, but my back doesn't feel all quite there. I am pretty long and lanky, so my backsquats tend to lean in a bit on the lowest part of the lift. Also, am I performing the front squats incorrectly? Is my shoulder pain (which I am currently feeling) inherent to the movement itself or just poor techinque? Also, should I try to encorporate reverse hypers and good mornings in my routine to improve my lower back strength and endurance? For back exercises I only do weighted pullups, dumbell rows, and deadlifts.
Thanks in advance.