It is possible that some of the more superficial bone particles are working themselves out, hence creating the feeling that you have. Normally, the bone should be well maintained and held in the site with covering membrane and gum tissue. Loss of bone material is not desired. You may see the surgeon who performed the procedure and make sure the site is healing properly. If this was done by a general dentist, I recommend an evaluation by a surgeon to double check it.
It is excellent that you are restoring a tooth with a bone graft and possible future implant. After a bone graft, some minor particles of minerals may disperse into the mouth during healing. The particles should be infrequent and small in number. There should not be bone particles pouring out of the bone grafted area. You should have a followup with your dentist to evaluate the success of the grafted area. Good luck and best wishes to you.
It is normal to have temporary "crunching," as the bone granules are expressed from the site of the grafting, but this does not usually continue for more than 30 days. I would suggest giving it sometime, then calling your dentist if your experience any pain or discomfort from these spicules. Good luck and I hope this helps. Follow me if you have more questions.
Sarah Thompson, DMD