teeth extremely sensitive, not cavities, black right above the gum? please read!

[Lolagurl]

ok i'm asking this on here because i have no health insurance anymore and i cannot afford to go to a dentist. i have had really painful teeth for about 2 years, i'm 23 years old by the way. i went to the dentist when this problem first started when i had health insurance and he looked at my teeth and said it wasn't cavities (i've never had any) and that i was probably brushing too hard and it pushed my gums down to expose the sensitive part of the teeth. he told me to use the toothpaste sensodyne and a soft bristeled toothbrush and it should go away in a couple of weeks. that was 2 years ago. i get an intense 'brain freeze' in my molars whenever i eat anything containing sugar, i can't even remember the last time i ate a candy bar. its getting worse, i don't really eat that much sweets anyways, but it would be nice to not have to explain to my friends why i don't want a piece of their candy bar. a couple months ago i saw that there is black right above my gums on my molars, i tried to scrub it off, it won't come off. i got my wisdom teeth pulled about 7 years ago and i recently found them and they have black stripes on them, i don't know if that happens to pulled teeth after a while, heres a link to the picture i took of them if it helps anyonehttp://i159.photobucket.com/albums/t149/Lolagurl21/Camera1542.jpg i took a lot of medication when i was younger for a health issue, including mass amounts of flouride which stained my teeth yellow, so i don't know if taking a bunch of medication can mess up my teeth. but if anyone has ANY idea what it is, please let me know. i've tried googling it but i can't find anything. it sucks, my sisters 18th birthday was 2 days ago and i couldn't even eat her cake. any help would be appriciated!!!

[ppyo]

I think that you should immediately visit your dentist .