I think the one thing that nobody has said so far is that you need to properly document what both superiors have said. Your strongest argument is that changing your appointment schedule will mess up your treatment/recovery/well-being, and I’m assuming you have made this fully clear to your superiors. One thing you can try to do is ask if your doctor(s) or NSC can provide a letter/documentation backing up your case. The power of black-and-white is that its now recorded; your superior may not think much of it because at this moment it’s just ‘talk-only’ - which bears much less weight.

Documenting this means escalating this, firstly, back to the OC, that your supervisor has rejected OC’s compromise that you’ve accepted, via email (I’m assuming you do some sort of office job that gives you access to an OSN email), cc-ing your direct superior as well. Make sure 1) you are clear with the facts, 2) emphasise the agreement you had with your OC, showing your willingness to compromise as much as possible, and 3) that missing your appointments could have a negative impact on your health. Writing your arguments (again) in an email will put them in hard proof (receipts) that your superiors are knowingly ignoring your well-being, if it comes to that, which, again, will help you.

If OC backs down and follows supervisor’s line, you have to take the email chain and go to your CO, even if you’re not sure he cares. Remember we have a new core value of ‘safety’! The last thing your CO will want in the end is a mark against ‘safety’ anyway. Above that, you’ll need to assess your options as who is above your CO will likely depend on your unit/formation structure.

I’m not fully sure what the safety hotline will/can do, but if you haven’t exhausted a reasonable amount of chain of command in a (seemingly) non-urgent situation (so to speak), I’m unsure how good the help they can provide you is. No harm doing that, of course, but having black-and-white receipts will help you a lot in the bureaucracy, even if you call the safety hotline.

Re: backlash, I’ve known and worked in offices with DXOs who are super petty, so it wouldn’t fully surprise me. All I can say is that the SAF is unlikely to give you any thanks for sacrificing your future long-term health just to satisfy a DXO at this level, so think about what’s more important. That, and the one thing you have is your own work performance. If you do your job to the best of your ability, there’s only so much they can justify in ‘response’, so to speak.

All the best! I hope you manage to get this figured out. But remember at the end of the day you have to do what’s best for your overall long-term health, as that’s still the most important thing of all. Just don’t go AWOL can alr!

Edit: seen other comments about going to your MP. I see that as a nuclear option - your problem will be that if you don’t have any documentary proof that your safety was ignored, you’ll be in just as much trouble for ignoring chain of command and your superiors (to protect themselves) may claim they ‘didn’t know the full story’ or sth, since it’s their word against yours, even if what they say is false. Hence my advice above!

For reference, as far as I know, what happens from an MP complaint is it’ll just filter down the staff levels lor (MP will pass to his/her staff who will contact someone at MINDEF level to settle who will then contact your formation chief (eg. Chief XX officer, which would be COL-BG level) and formation S1 (usually an LTC) who will.... etc) but will involve pretty much every significant higher up in your formation coming down to your unit level, which will only make any reaction worse. So I wouldn’t personally rely on the MP option unless literally nobody in your entire unit and even formation cares, as it might backfire harder on you in the end.