My sciatica creates unbearable pain. My sacrum (sacro-iliac) goes out so easily, I have to not push, pull, lift anything above 5 lbs (3lbs is safer for me.) I can't do stairs as that can also pop it out; if I must then I have to do bad side (leg) down then the other then the bad then the other leg...at an angle. It helps greatly. My physical therapist taught me many ways to prevent the sacrum from going out. (The sacrum goes out and presses on the sciatic nerve...either side and sometimes both!)

I also found that when the sacrum goes out, the surrounding tissues swell up in reaction. If I ice up and also do some stretches, it might prevent the sciatic nerve from being involved. Otherwise, I take an anti-inflamatory. I've lived with this chronic pain since my injury. I say all this because my pain can often be off the charts (above level 10) yet I refuse surgery until they figure out what works for me, forever...etc hehehe
Do see if you can work with your physio for relief. I'm very glad you found someone who validated you...that means so much! Maybe your physio will help educate your MD.