this thread is really old, but i happened upon it and would reply anyway. this also happens to me,just like described above with it being very low and deep in pelvis...and while i have no idea if this is true, my theory has been that the humming buzz is when the big worm is laying eggs. it just makes sense because it happens like once a month and for like 15 mins. so disgusting! this worm thing has been the biggest nightmare of my life.