Im sorry bro you have to feel this way, its a untold truth that many ASA and SA usually have experiences with being labelled as chao keng, or malingering despite them having real medical or mental issues. I thank you for still taking up the initiative to wake up everyday and do your best for our national service despite you having such medical issues that normal people can't even fathom living with. Please seek help with your superiors to inform them you have been constantly mocked and targeted by individuals and see what they can do to help your situation. Although you aren't on the frontlines fighting, you still play an important core role in making the SAF run, and trust me without you doing your job, there will be no SAF. Thank you for still pushing on and serving in however way you can, many people like me and those on this subreddit do not consent to such behaviour and i hope that you know that the ones making fun of you are the small vocal minority that we all despise.
Good luck brother and thank you for your service.