I want to say I have had bad teeth all my life and well .... Anyways you may cringe at me when I say this but this is how I stop a root that hurts and show. Ok here we go don't laugh but will work but hurts like hell at first and when your freaking out to the point I'm going to pull it my self well here is how I fixed my problem.
I took a tooth pick like at the dentist office uses but sure something clean and sharp would work. Here we go... Stand in-front of a mirror for this as have to hit directly where it is hurting so mirror is best place and yes you have to look. Take the tooth pick metal and heat it red hot with a litter like red and pock it in their on the root and you will feel a sharp sudden pain hold it their because you will notice the pain becomes faint. Take the pick of after 10 15 secs rinse mouth out with salt water and you will notice pain is gone all you feel until it heals is a thumping with no pain :) TRUST ME IT WORKS I HAVE DONE IT 3 TIMES AND ALWAYS WORK. You kill the root by catheterizing it. Back in the 1800 hundreds is how they did it until they got it pulled. You may forget about the tooth but don't get it pulled as now its dead almost completely.