Hugs, bone marrow biopsy are the worst. I had one a month ago. My marrow was mushy, so the hematologist had to keep going back for more to have enough of a sample to test. I was sore for a week afterwards. One thing I learned after the fact, that it is a good idea to take to Tylenol Extra strength or percocet about an hour before, it helps mitigate the pain during the procedure.
To get the marrow and a marrow blood sample they need to drill through the bone which is covering and protecting the marrow.