i was using a toothpick bc i thought i had something in my tooth. and now it feels like there is a gap between where i used the toothpick. i look in the mirror and notice around the base (close to gumline) of my bottom two incisors that it appears very white like there is plaque on it but there isnt. it feels bery brittle, if i pick at it im afraid it will break off. is this a cavity? it does not hurt it just feels verrrry brittle and rough edged, and whiter around the base near gumline. please help!