Hi, I had a cracked tooth with no infection. Then I had a root canal six weeks ago and they placed the permanent crown three weeks ago.

Yesterday I noticed a small red swelling under the tooth, it's the second to the last bottom molar.

It looks like a pimple and it's a little tender but doesn't really hurt.

I tried to look it up and some sites said this is common and should go away on it's own in a few days - others said that even if it does go away it will come back and the tooth will have to have more treatment. Which is right?