Hi and
Sorry to hear that you're in so much pain

. Root canal treatment is done for a variety of reasons; usually because the pulp (the very inside part of your tooth which contains the blood supply and nerve tissue etc) has become infected or inflamed due to infection, decay or injury to the tooth. We have a page with some information about root canal treatment here:
Get detailed answers to FAQs: Is root canal treatment painful? Why am I sore afterwards? Why do I need a crown? And many more!
www.dentalfearcentral.org
It depends on what's causing your pain as to what the best type of treatment might be; only a dentist would be able to tell you for sure. Root canal treatment is a pretty major thing to do to a tooth and once it's done, there's no going back because it can't be reversed. However, if it's the right treatment for the tooth and it's done properly, then it can get rid of the pain and the tooth can last many years if it's properly restored (with a crown or filling) and properly looked after.
It's not unheard of for people to need several root canals, but it does depend on what's causing the pain as to how it's treated. I had severe acid reflux about 12 years ago which eroded the enamel from the biting surfaces of most of my molars. It wasn't too bad at first because I only had sensitivity to hot and cold, but as things progressed, the pain got worse until it became painful to chew anything other than soft food. About 3 years ago, I started having severe pain in one of my lower left molars and it wasn't eased by painkillers. My dentist at the time tried various things, including bonding fillings to the tooth, but nothing worked, so he suggested a root canal. After I'd had the root canal, the spontaneous pain settled down and I could chew on the tooth again, however things were still very sore whenever I had hot food or drink. The rest of my upper and lower molars remained pretty sore and painful too, although the lower molars were worse.
Several years later, I decided to change dental practices and one of the first things that I was told was that the previous root canal hadn't been done very well and it would need to be re-done before having a crown on the tooth. The previous root canal experience was less than pleasant, so it took my dentist a whole year before he managed to persuade me to let him refer me to an endodontist for the root canal to be re-treated. At the beginning of January this year, I started having spontaneous severe pain in one of my lower right molars which continued to get worse and so my dentist ended up removing some of the nerve from the tooth to relieve the pain, but of course that meant that I needed another root canal in addition to the one to be re-treated.
I went to see the endodontist at the beginning of February this year for the initial consultation and I booked a couple of appointments for treatment. The first treatment appointment was scheduled for the middle of March, but in between the initial consultation and the start of treatment in March, the tooth next to the one that my dentist treated in January, also became extremely painful and so I ended up having the nerve removed from that as well. By the time I went back to see the endodontist in March, I then needed 2 new root canals plus the old one re-treating. I've been having root canal treatment either every week or every other week since March because during this time, I've started having severe pain in several of my other teeth as well. Sometimes, even though it was only one or two teeth which were causing the problem, the pain was spreading throughout all of my upper or lower teeth at times (it's called referred pain and is when the pain from the affected tooth spreads into the teeth next to it as well even though there may not be a problem with those teeth - I think it's something to do with the way the nerves in your jaw work).
To cut a very long story short, I've ended up having 6 root canals (5 new ones plus the old one re-treating). I've still got a couple of appointments to go because one of the root canals needs to be completed and I need the permanent fillings in a couple of the other teeth, but once it's all settled down in a few month's time, I will then have crowns on the teeth. In my case, the pain was caused by pulpitis (inflammation of the pulp inside the tooth) which had been going on for quite a while and had been getting worse, so root canal treatment was really the only option other than losing the teeth. Apart from a bit of soreness in the tooth which needs to be finished and also in a tooth which was recently completed, the root canal treatment has pretty much got rid of my pain completely

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I think it's possible that things can go wrong all at once because they have done for me

, however if your pain still continues and given all the problems you've mentioned with the existing treatment, maybe it might be worth getting a second opinion to get to the bottom of what's causing the problem. Root canal treatment isn't something that you want to do lightly; you need to find out what's actually causing the pain before deciding what to do next. You only want root canal treatment if you actually *need* it.