Hi Diane37,
Unfortunately this could be from many causes. Too firm could cause them from excess pressure, too soft could cause them from creating a more “hunched” position when you are sleeping, and it could also be a pillow issue. Post #2 here has more about some of the more common symptoms on a mattress and some of the possible causes but it can take some trial and error to isolate the cause. Is there a specific layering out of the three you’ve tried in this thread that seems to produce the symptoms more than the other two (that might provide a clue)?
Phoenix