Do I have symptoms of a failed root canal?

hi all,

So about a month ago I got a root canal on an upper anterior tooth due to decay and exposed nerve that was underneath my permanent retainer (now removed). First week after treatment was fine no pain, but now 4 weeks later I'm starting to get a throbbing type of pain deep in what feels like the root of the tooth (pain scale probably a 4/10); and when I floss around it only that specific tooth starts to bleed. Saw the dentist 2 days ago for a general exam and full head x-ray and I mentioned my symptoms to him, he's also the one who did my actual root canal.

He x-rayed the tooth up close and said he couldn't find or see any evidence of infection, nor any other reason for my tooth to hurt. He was showing me the X-ray when he was saying this. He didn't seem overly concerned, but I'm starting to worry about it. Should I go back to see the same dentist and push harder about it, or should I get a second opinion at this point? I'm really scared because I already used ALL my benefits for the root canal, I already need a loan for the crown and I can't afford a re-treatment root canal without getting another loan from the bank...

*key note, the tooth has not been crowned yet. I was preparing to make an appointment for crown prep but then the pain started, so I canceled it.*

x-rays pics not available unfortunately my apologies.

thanks in advance.