I am also from the u.k. Like you I have only had X-rays done, I was told my tmj was caused by grinding. But most people on this forum seem to think that a x-ray isn't good enough and that you need an MRI to really see if there is any damage. I have had tmj for about 6 years now and have a lot of pain but the dentists in the u.k have not even mentioned having a MRI, it seems to be something they do in america more. so I am thinking of asking for a MRI soon, if you have pain in the future you should maybe suggest about having a MRI as well.
I have also had phantom tooth pain, I had four wisdom teeth removed. I have had a really sore gum in the past but it isn't too bad at the moment. When I brush my teeth I have to do it really softly or the pain can start up and last for day's. My sore gum is where my last wisdom tooth is so I thought it might have something to do with that but the dentists told me it isn't. But you only to read story's on this forum to see that dentists do get it wrong sometimes about wisdom teeth. Anyway I'm pleased you are feeling better and I hope the mouth wash continues to work for you!