Tooth Pain and dentist sees nothing wrong

Tooth 12 was extracted yars ago. I had tooth 14 molar extracted 3 weeks ago So tooth 13 is by itself. I woke up in the middle of the night with  bad pain  in that tooth  and it still hurts hours later.  Was teeth clenching or maybe stress  on the tooth or sinuses causing the pain? The dentist took xrays and examined the tooth and he could find nothing wrong with it.  I felt  no pain on the dental pulp test but even my healthy teeth  responded the same way so he does not think its a root canal issue. He is rather stumped. he filed down the tooth so it does not hit on my lower teeth  and gave me prescription tooth paste  but tooth still hurts.  I do suffer allergies  and have sinus issues alot. I wonder  if  my sinuses are maybe irritated  and not  noticing it???