Unable to open mouth more than two fingerbreaths for root canal so endodontist quit!?! had to see his jr partner.

Why? Why couldn't you open your mouth more than that with the first dentist? Did you open your mouth further for junior? If you did, you had something against the first one, whether you were conscious of it or not. Fear or anger has many faces.
Patience is key. Acute dental infection often causes "trismus"-- limitation in the jaw's range of motion, by inducing spasm in the jaw muscles. It is often helpful if your endodontist administers antibiotic and waits for the more acute manifestations of your infection to resolve, at which time you will be able to more easily open your mouth. This will allow endodontic treatment to proceed more quickly and easily.