I started to have this problem when I moved to low carb diet (~50g per day) + exercise. Exercise was mainly very very fast walk, 30min - 1h per day with some ocassional HIIT (2 times per week). The goal was to loose some pounds which I succeeded (~15kg for 6 monhts) and to resolve some dermatology problems (eczema, dry skin, itching after showering). I have supplemented my diet with bunch of high quality vitamins and minerals. I was also taking lots of D3 from Merck for babies (50K IU for a week, dropping to 30K IU next week, dropping to 10K IU for a months, dropping to 5K IU for next month, then stopped; was using 50-100mcg K2 with it and Mg). My Vitamin D level currently, after all that supplementation and 1 month of life near sea is 84.2 nmol/L (33ng/L) which borders to deficiency AFAIK.
Now I have crepitus. Its not a big thing, but its annoying and my left ankle is particularly problematic, cracking after every footsep on the uphill or each squat.
I tried to stop D3, added 1 month more 100mcg K2 MK7 / day. No change, only stopping exercise produced effects. Tried 2 months of MSM, glucosamine, HA, no help. Uppped starches and chocolate - no change.
Any suggestions ?