Back squats

Back squats up to 135 for three sets of 5. I felt a little weak, less solid than usual at this weight that is routine / medium for me normally. My knees and hips were achy. I’m still coughing but nothing worrisome. I lost two pounds in January: one pound before 1/15 and one pound after I was sick. I was doing the Whole30 all month, so it’s not necessarily because I was sick that I lost two pounds; and two pounds is not a lot regardless. So, how much strength have I lost? Is it torso fatigue from coughing that made the squats feel so much less stable? Or would I have lost strength in my legs? It’s hard to tell.