I just got mine today at
-- I am also sure you could get some at a health-food store.
What I do with mine is to use several drops (4-6) in whatever oil I am using -- these days, usually sesame (which is also antibiotic). Then just swish per your normal routine.
Try to stop sugars while you are working on this as they will a) prevent your immune system from working its hardest and b) will cause inflammation, preventing the gums from healing close to the tooth and keeping the bacteria out from between the tooth and the gums. In addition, stopping sugars as much as you can will prevent teeth from developing cavities.
Another thing that will help knock out a mouth infection is xylitol. You can order it or buy it at some health food stores. It's what sweetens Dentyne, and is a natural antibiotic, too. You can rinse with some xylitol in water several times a day. (You can also find xylitol gum and hard candies online.)
Another thing is Vitamin C, which will help your body fight infection. I get bulk C ascorbate at Allhealthtrends.com and also I use Emergen-C packets.
You can take medication and still get OP benefits. I took medication last summer for migraine and as far as I could tell, both the meds and the OP worked just fine!
Maybe you could try this stuff for a month or two and try going to a different dentist to see what he or she says about that tooth. My prediction is that the present dentist is not going to back off of a root canal
diagnosis, but that another dentist looking at a tooth treated by OP and other things you try may just find a tooth that can remain as is.