I was brushing my teeth this morning and i saw something that hurts when i touch it, what could it be?

Saw what?: I'm not sure what you saw and therefore can't tell you what it might be. Have a dentist take a look at "it". Please repost your question with more information.

See your dentist: There are many reasons for someone to develop tooth sensitivity or pain. Some common toothache causes are dental cavity, gum disease or teeth grinding. However, a suddenly sensitive tooth or teeth can be symptoms of another problem. If concerned, see your dentist for consultation.