Bad Dentist? Dental Negligence?

I'm really frustrated and hoping for some advice. I don't have dental insurance. Nor am I by any means rich (work for a church). I had to find a new dentist in metro Boston (I've been in Boston for 6 years now and was still flying to Maryland to see my family's dentist every 6 months...). I did my research and found a dentist who participated in a dental discount network to help defray the no-insurance expense. I knew I had two cavities from my previous dentist. I had them filled by the new dentist. New guy said there was a 50/50 chance that one of the cavities he filled would need a root canal. A week later I was in serve pain and needed a root canal ($1,000 + another $1,000 to have a crown on afterwords). New dentist also said I had three small cavities that should be filled, but not to worry none of them were near the root. Knowing that small cavities become big ones, become root canals - I had them filled. Now one of those cavities is showing the same pain symptoms of the other cavity that needed a root canal. I absolutely don't have another $2,000 to pay for it. I may be reaching, but I'm questioning if this new dentist has filled these cavities in such a way to make the chance of needing a root canal higher (after all he gets the $$ for doing the crowns). i.e. Is he drilling deeper than necessary (making the opportunity to disturb/infect the root more likely?). The combination of a few things have made me skeptical about his competence: 1) he participates in this discount network (wouldn't a good dentist not need to offer discounts?) 2) the office is rarely busy and they always seem to have openings the next day, week, whenever 3) it's not the nicest, cleanest office 4) i found zero information on this dentist (albeit positive or negative) 5) I'M IN PAIN Should I see another dentist and ask if these cavities have been properly filled (which will cost more $$$)? Should I confront the dentist? Meanwhile, I'm in constant dull pain, $2,700 in the hole from dental work (potentially $4,700) and NONE of these teeth hurt to begin with. I feel like I've been taken advantage of, knowing that I want to keep my teeth in good condition and being squeezed for ever non-insured penny I have. It's keeping me up at night (the money and the feeling of being ripped off). I'll have to sell my car in order to have ANOTHER root canal done. What do I do?
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I think all of your points answered your own question. You get what you pay for. Be careful on specials for brain surgery, parachutes and dentistry.
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