I had to undergo a root canal when my tooth was so decayed that part of it chipped away. It got to a point where I would get fevers and headaches and some jaw pain. After the root canal I noticed those symptoms still. It went away after about 1.5 months. I guess maybe your husband's brain is still creating those symptoms and it could be his sub-conscious mind.
It could also be something else but this is definitely a possibility. Hope he gets well soon.
Thank you for the reply! For the sake of money, I hope it's all in his head but I hope he doesn't have to suffer with these symptoms for long. I looked at his gums yesterday around the tooth and they're not red, inflamed, or swollen so it doesn't appear to be infected to me. He made a follow up appointment with the endodontist for tomorrow. The endodontist did mention when he was there last week that it may have been a wisdom tooth that was causing his pain. My husband asked if they could start with removing the wisdom tooth to see if that did the trick and the endodontist took another x-ray and stated it had to have been the tooth and performed the root canal anyway. I'm hoping he didn't do this just so he could get paid instead of trying to remove the wisdom tooth first. So it may come down to having the wisdom tooth extracted and hoping again that solves the problem. We'll see what he says tomorrow. Thanks again for your response, it makes me hopeful that this can go away on its own and isn't necessarily a larger problem.