unfortunately it is totally and utterly random... what some doctors may refuse others are totally willing to do, and more than a few like to do dangerous procedures when conservative treatment will suffice
sometimes you can actually get an insurance company to help you get the right treatments instead of something outlandish ... yes, you are well down the rabbit hole now
just keep doctor shopping until you luck into the ones that will work with you - they do exist
i totally bumbled into a physiatrist at samitivej srinakarin who has basically saved my life, the orthopedic surgeon who sent me to him is a ding dong ... so this was truly and utterly dumb luck
also: there are imaging centers here where you can get full body imaging without a prescription.
and you can try the lesser known private hospitals ... praram 9, ramkamhaeng, etc ... they are often willing to do imaging with no argument. their doctors love to do any possible diagnostic they can but tend to favor conservative treatments (and nutraceutical polypharmacy but thats another issue).