Help dental assistants/dentists,i had 3 months of pain in back tooth,has the infection spread is this dangerus?

Hello,i have had pain in my back molar for nearly three months now,it started when i ate anything i got vicious pain,so i chewed food on the other side,and took painkillers,i didn't go to the dentist straight away as i have no dental insurance,now last week it got very bad,i went to a dental hospital and they took xrays and i said i have a abscess,and that they could not do a root canal as its students and it is to complicated on a back tooth for some reason. Now i am worried in all that time i left it the abscess could have spread i have pain in my head and cheek and ear. So i went to my reg.dentist and she said it can have a high failure rate as reg.dentists dont have specialized equipment but they can do something called a 'PRIMARY endo' to relieve pain,until i can get the money together to see a specialist which might take 4 to six more weeks,is this safe?? She said a specialist uses hot liquid rubber filling solution to reduce risk of bacterial infection,and they use cold rubber filling solution and its difficult to clean the bacteria from the small root canals and likely to become reinfected as the awkward position of the tooth. In your opinion what should i do,should i do this primary endo and wait 4 to six weeks to save up for the specialist,could the infection get worse?or not do it and stick it out until i can getthe money together,i am just scared the infection could get out of control,any warning signs i should look out for?The reason i dont want it pulled is that i have 2 teeth next to it missing already and this tooth has a crown which was expensive,it is a heavily filled tooth underneath the crowm,but its not due to decay that caused the abscess they said,please any advice i would appreciate so much i am very scared and would like some information thank you very much
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I also have an infection underneath my back molar but the dentist gave me a prescription for antibiotics. She said they should clear it up before I have the tooth removed. Maybe you should enquire about getting antibiotics? They worked for me:)
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