Pain months after root canal

[Yogamom58]

I have discomfort in my tooth when I tap on it or when I push on the root next to the base of my nose. I had a tooth and segment of bone removed 30 years ago for overbite. About 2.5 years ago, the tooth (#6 I think - upper right canine) turned black. I had a root canal and bleached the inside of the tooth.  About 6 months ago I noticed that the tooth was turning black again, so I had it bleached again and di a few days of external whitening with a tray and gel. Shortly thereafter I started having started having pain when I tapped the tooth (#6) that had the root canal. My dentist thought it was unrelated to the bleaching and prescribed a round of antibiotics. The pain went away. I recently (a couple weeks ago) remembered that I was going to do a touch-up bleaching on my teeth and did a couple nights of bleach with the tray. (Note that I do not bleach regularly, this was the first time in 6 months since the last incident and before than after the root canal). Now again I'm having pain when I tap #6 tooth and also the adjacent tooth (#7), worse in #7, and also pain near the base of my nose when I press it. Is this most likely an infection again? Does root canal make infections more likely?  Would the bleaching have anything to do with the infection?

[scottma]

Bleaching material probably would not cause infection.but it may cause gingival irritation . Seeing an endodontist is advised.