I have braces for nearly 2 years now.  I have never had any toothache
problem.

But, a few days ago, tooth number 26 (http://www.ada.org/public/topics/
tooth_number.asp) started to hurt when I eat/drink, the pain seems to
be worse if the food/water is very hot or very cold.

My ortho says that it might be because tooth 7 is biting on tooth 26
too strong, so he made some adjustment to them this morning, but it
still hurts.

I have never had this problem before.

I have made an appointment with a dentist for this coming Thursday.
Before I go see him, Is this suggestive of a cavity?