Im having a problem with my lower back while training lately. Now I have been on a kinda long break due to becoming a father and being laid off. The only way to describe it is that my lower back feels like it "blows up" after only a few reps of deads and squats. I remember this same feeling after higher rep deads and squats before. The only difference from training before and now is I am doing a lot more sled pulls and light tire flips on off days. I got kinda fat after a long break and need to slim down quite a bit. Has anyone had this problem and how did you "fix" it? Thank you in advance.