Crowned tooth might need root canal- Do I have to pay for a new crown after the root canal?

So I went to this new dentist strictly because they had late hours. Well they put in a temp crown while my permanent crown was being made... and that night (within 4 hours after I left) it fell out when I was just sitting there watching tv. So I went back a few days later. They put another one in. That time less than an hour after I left it fell out. So I was again for a few days without a tooth in the back of my mouth and unable to eat anything hot/cold and barely was able to brush my teeth. Because they messed up so many times my teeth (recently had 4 years of braces removed, too) moved a little and now my teeth are a little messed up on the bottom. So since I had my permanent crown put in I've had tremendous pain each day on that side of my mouth. He took an x-ray, said "Hmmm... I'm not sure why that one tooth is shaded a little darker than the others" and gave a little chuckle and sent me off with ibuprofen. I went back again because there was still pain. He made me buy a $200 mouth guard that falls out because it doesn't fit right. A few weeks later I went back still with the pain (that if I don't take at least 4 ibuprofen I literally cry in pain) and he said he wasn't sure what it was and I should ice it a little. Btw, my mouth on that side is a little swollen, too. Noticeably. And has been this entire time (several months) I am running out of prescription pain pills from my neurologist who felt bad for me, so I called a few dentists to try and get their opinion. Over the phone the lady said it sounds like I need a root canal on the tooth with the crown but I need to first go back to a regular dentist to get a referral (awesome how my current dentist saw me more than 6 times in a month and a lady on the phone knows more about my teeth than he does). I won't have dental insurance next year, so I need to do all of this work done preferably this year. My question is this- since it was his fault for not checking my tooth before putting the permanent crown on, does he pay for a new crown to put over the tooth again after the root canal? Or do I get the root canal, and I have to pay another $400 (if my insurance covers as much as last time, which I doubt it, so more like $800) for a new crown and go through all that pain again? Or if I get a root canal on the tooth with the crown, does it have nothing to do with the crown I have in now? Any advice on this topic helpful. Thanks.
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As a dentist I am not going to get into the charges you are asking about. All I would suggest is to find another dentist who is better at diagnosing and doing treatment.
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