My left knee is weak and has been injured a few times before. It hurt before my workout on Wednesday(new x5 squat PR, so heavy for me). Both of my knees hurt after. I don't think my form is the issue. Thursday I was hiking around in mud wearing rubber boots and digging holes for three hours. Both knees still hurt today, but feel better than yesterday. I have 5x5 with lighter squats and heavy DL tonight. My question: Should I stick with the plan and see if my knees can stand it or work upper body and give the knees a break? I was planning on going for 405 tonight on the DL, but I have ruled that out.