what is wrong with my teeth

I have seen various dentists and they say nothing.
all of my teeth are discoloured yet i brush them twice a day.
my teeth are literally falling apart pieces keep falling off of my molars and my front teeth appear to be chipped cracked and discoloured. I have all my molars filled this was done as a child and has since been re done. i was extremely ill as a child with meningitis and one dentist said it could have effected the growth of my permanent teeth. the enamel has worn off and i dont open my mouth to speak.
also the teeth at the gum are eroding and black/brown i am in constant pain but each time i see a dentist they just look at 1 tooth maybe re fill it and the thats it.
i have had continual pain for 4 months now with no relief from pain killers or anti biotics i was just wondering if there is any information i can take with me to a dentist to get some help.
the pain is so severe i have become isolated
thankyou

[Jerome Tsang, DDS]

Have you considered going to a dental school or other teaching institution to get a second opinion on the matter if private practice isn't working for you?  I don't see why they wouldn't treat you if you have symptoms and problems.