Hi catfish baby,
Unfortunately, I don't think that there will be a TMS doctor that would be likely to convince you that your spinal area symptoms are TMS. I say this because most are not back experts, albeit that some of them might be able to tell you about patients of theirs who were diagnosed with Modic 1, but their pain went away once they had managed to convince themself that modic 1 wasn't responsible for their pain and it was TMS. The only TMS back expert doctor that I know of is Dr David Hanscom, a back surgeon who had been suffering back pain himself who taught his brain to stop giving him TMS, but I don't know whether he sees TMS patients personally, but he wrote a book about his experiences and here's a link to a webpage about him
https://mytmsjourney.com/experts/dr-david-hanscom/ (Dr David Hanscom), plus here, on his website, he mentions modic changes
https://backincontrol.com/surgery/decision-making/non-structural-problems/ (Non-structural Problems)
I watched the modic 1 video and noted that the treatments for it are either with drugs (that will have the potential for side effects) or surgery (with the risks that would also entail) and that there are differing opinions as to the cause of causes of modic 1, which means that you wouldn't know for sure what the best medical treatment would be for you if you were to go down the medical route. It would obviously be something that you would have to judge for yourself - try to judge which expert you believe as to whether the cause of your modic 1 is autoimmune, mechanical or due to infection.
I note, however, the video concludes with the advice that
"the best thing you can do is live your life as normally as your pain allows" and that's generally the very same advice given regarding TMS, so it doesn't appear that you have anything to lose by following that advice.
I've read Steve O's book and was alarmed at how he half killed himself with so much running, golfing etc., to convince his brain that he was safe and that each activity was safe for him to do...and he got better. However, I also read somewhere - can't recall where - that he doesn't now recommend a 'hell-bent for leather' approach like the one he took. So, my humble suggestion is that you get on with life as best you can, forget about running for a while, whilst you look for evidence that your symptoms are TMS and endeavour to reduce your stress levels.
A start might be to keep reminding yourself that some of your symptoms have come and stayed for a long time and then have eventually gone, only to be replaced with other symptoms, and that some of your symptoms have come and stayed and then gone and then returned - which are all hallmarks of TMS (albeit your brain will almost certainly come up with all sorts of other reasons to explain and try to convince you otherwise). I would consider too that the improvement for a while with your SI area symptoms may have been to do with your faith in the physiotherapy and the physical therapist helping you at the time and that perhaps they returned after you finished attending for physio - not sure if that's the case or not, but this is the kind of thing that you need to look for.
Videos that might help you prove to yourself that you are suffering TMS (with thanks to my wonderful friend
@Marls for recommending them to me in the first place):
Also, I recommend noticing the thoughts that pop into your head...are they a lot of doom and gloom, fearful or otherwise unhelpful? Do you believe most if not all of the thoughts that come into your mind and/or then let your mind run away with more and more related thoughts that are also far from helpful?
This video has helped me a lot to detach myself from such useless and symptom-inducing thoughts:
Also, Dr Sarno said to talk to our brain, to tell it to stop producing symptoms - for some people that works well, so it's worth a try.
Best;
BM