who should i try to ask for another opinion if i'm unhappy with the way a dental procedure was done?

i had my second root canal done last week by another dental group, due to insurance changes. my first one was done by a specialist, and to me, was done much better, and with more care and professionalism. the tooth that i went in for was a molar on the lower right side, which i was told was cracked in several places, with a large crack running to the gum line with a cavity at the end. i was given a "long" acting numbing shot on that first visit, along with rx's for penicillin 500mg and a pain med, and told i needed a root canal which would be done a week after being on the antibiotics. i had to call back the following monday because i was still having alot of discomfort, and the only change made was to the antiiotic, which then was cephalexin 500mg. this was done reluctantly, as i was told their office had a history of patients not showing up for procedures. initially, i accepted this reason, even though i had already given this office 2 post dated checks for the procedure. i was very anxious about the procedure, as i kind of am with any i've had in the past. i asked to pay for nitrous (gas) to be used during the procedure. (ins. won't cover that). i went for my procedure, (had been told by dentist he had someone that came to in to do these), had been given rx for anxiety, but i didn't take it as i figured the gas would be enough. something didn't feel right the moment i sat down and was examined with the tapping. i felt like he hadn't done many root canals at all, and this was even more so after 3 attempts with the gas, i didn't feel any gas at all. he said that something must have been wrong with the machine because he had turned it up as high as it would go, or my tolerance was extremely high. i don't know how true that is, because when i had my previous root canal, i had to ask the specialist to turn the gas down. twice i had to stop him during the procedure, the first because saliva was pooling in the back of my throat, and half way through, i felt a very sharp pain radiating into my ear. i was given another shot for this. i was told after it was over, i would need no medication other than ibuprofen for 2 days for soreness. i've had discomfort for a week now, am running a low grade temp and called them to talk about it, and was told the dentist i initially saw was uncomfortable doing anything about it without me being seen today. my followup was supposed to be thursday, but i do not want to go back. what could be causing the discomfort still, as i can't put pressure on the tooth. who else should i try calling? what can i do in the meantime? should i have been told if the person doing the root canal hadn't had much experience?
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Ask another dentist.
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