The ignorance people have surrounding invisible illnesses is astonishing. Sometimes, there can be no greater suffering than being perpetually tormented by the "mind" as we call it. Though I think that labelling malfunctions of the brain as this intangible, distinct psychological thing, a separate construct of mental/psychiatric illness that is distinct from neurological disorders, achieves nothing but doing people who are suffering from them a large disservice.
Any thought, feeling, emotion, or signal of pain all stems from the brain, a physical organ. Just because we have no way of empirically measuring such cognitive states does not make them any less real, but unfortunately there is culture of individualism in most places that purports one can control their own destiny with willpower alone, including their mental state and outlook towards the world, even when scientific evidence begs to differ. I know how completely pseudoscientific this is because I have a neuroscience degree, while many laypeople get their information from pop psychology clickbait online and never actually read any clinical literature about the brain and how it works.
This phenomenon has actually been studied before, and it has been proven that people can cope better with illness when their pain is acknowledged and taken seriously by authority figures (I.e. doctors) as well as the community that surrounds them in their personal life. Unfortunately a huge driver of how seriously someone's ill state will be taken is influenced by how the medical community views their symptoms, and if they have a diagnosis which garners empathy and support in the perception of others, something which can visibly be seen typically. Yet by creating this culture of shrugging off invisible and misunderstood illnesses especially if they are considered mental in nature, it is actually having negative knockdown effects and making everything worse.
I sympathize with your plight completely as I have had PTSD since I was a young child and people have always acted like I can control it or wish it away, that it isn't actually real. Also, I have had strange health problems for almost a decade now that stole my youth away and have irreversibly ruined my life. Because diagnostic tests have been inconclusive, most people do not take it seriously and think it's either fake or I need to get over it. I've had chronic pain for years and 0 pain management offered except generic NSAIDs.
Now, compare that to how I was treated when I had multiple large tumors, and the medical staff didn't know if I had cancer yet or not. It was like night and day. Top of the line pain management before surgery, more compassion, for once other people actually acted like I had a "valid" health problem. Despite how bad the whole ordeal was, I would say years of chronic illness was and still is worse than having tumors in my own personal situation. And my tumors completely made me unable to use the bathroom unassisted for a long time. I would take going through those few months again any day over the years of suffering I've been through otherwise.
At the end of the day, these misconceptions stem from how the public perceives certain illnesses as worse or more real than others, and how fatality is perceived as the worst outcome rather than prolonged, incurable suffering. There are people I have known in my lifetime who don't get a single day of peace due to mental illness or chronic pain, constantly being tormented by horrible symptoms. Then I have also met people in my life who had certain types of cancers (which is something I learned about quite extensively in my degree as well) who don't even have to undergo chemotherapy, akin to my tumor situation, they have a single operation and it's over and done with.
You can guess whose situation would be perceived as worse though, even though one person is living symptom free and with low risk of pathologic reoccurrence, while the others are in the throes of suicidality. People are just widely misinformed and think that depression, or PTSD, or anxiety, etc is just feeling low for a couple days and sorry for yourself, not grasping the spectrum of suffering than can occur. Likewise, they'd view ALL tumors as something completely incurable, intolerable, and fatal, even though with modern technology and surgical techniques more and more types of cancer and benign growths as well are highly treatable, similar to how HIV became clinically manageable with the advent of anti-retroviral drug therapies.
