Struggling with Medical Issues and Reliance on Parents

I’ve been experiencing a lot of medical issues regarding my physical health. With pain in just about every part of my body, some days worse than others, and a newfound discovery of low blood sugar, I’m struggling to function day to day. I’m tired of being in pain but I am, unfortunately, still reliant on my parents regarding medical care. They’re very strongly against anything other than holistic health care and do anything to prevent me getting diagnosed for any of these problems. I know I’m an adult, but my current lot in life prevents me from really stopping this. Any suggestions on how to ask for help? Because the thought of being vulnerable to these people terrifies me to the core