I think i have cavity in my lower right side second last molar , the cavity looks small in size from outside, i can feel a hole in that tooth when i glide my tongue over it, also i feel pain i.e low to medium intensity pain plus sensitivity. Medium pain only when eating, brushing etc and low pain when nothing in mouth. However , there is no pain when grinding teeth together. Do i need cavity filling ? I am attaching pictures of the tooth . Your opinion on this will be much appreciated. Thanks.