My friend had the same thing start happening, after she did a 90 day challenge. It started with the creaking/grinding sound and developed into a knee problem. Glucosamine and working the supporting muscles (quads and hamstrings) helped her. I have had an ACL tear on both knees over the last 15 years. I went to physical therapy for the first one and it recovered, but I started over compensating with the other and tore it a few years later. I am now very aware of them, when I exercise. I also take glucosamine that helps cushion the joints, I also try to take a yoga or stretching class once a week. I have been able to stay active, without surgery!

I've had creaky knees since my late twenties. I blame it partially on tennis that I played pretty avidly when I was younger and on climbing up and down hundreds of spiral stairs at once at this extremely tall church in Germany that I visited. Walking up, I thought I was fine; coming back down, I soon was in agony, but what can you do? No elevators in hundred year old buildings! Anyway, the creaking actually seems to have reduced and is mostly gone now. I don't know whether to attribute it to my weight loss, exercise, or a the combination of the two, but I'm glad. The sound and feel of it has always freaked me out.