How do I stop sever root canal pain? I'm allergic to lidocaine and no dentist will work on me. This is my second time going through this pain.

Endodontist. Please seek the services of a root canal specialist. There are other anesthetics that can be used.
Endodontist. Endodontists have special skills to treat such patients. There are anesthetic agents besides lidocaine. You can also see an allergist to test for allergy to lidocaine. Many patients who state they are allergic to "caines" are not when tested.
Vague. I am confused when you say, "no dentist will work on me." there are some Lidocaine alternatives or even considering sedation dentistry. Have you been referred to an endodontist, a root canal specialist?
Lidocaine allergy? While possible, I have yet to have a patient truly allergic to lidocaine. More often than not, patients have a reaction to the Adrenalin in the local anesthetic and say they are "allergic" to it. There are other types of local anesthetics available. See an allergist for testing. Research endodontists in your area. Perhaps a local dental school or hospital based dental residency program.