How can I get treatment for an aggressive illness?

About four years ago I started having, what appeared to be, non-multiple sclerosis neurological symptoms. My MS was slow progression and then frozen with mavenclad. Many tests and blood work gave a diagnosis of multiple myeloma. For about six months all confirmed that diagnosis until I got a bone marrow biopsy. Test came back negative and the diagnosis reversed. Now, all squirrelly abnormal results are seen as "normal" form me. And the symptoms treated with a fistful of pharmaceuticals. Unfortunately, I keep getting worse overall. Nothing seems to ever appear in scans or tests. Anything that appears gets retested until everything can be explained away as some known condition or old age, (I'm 64), or something. But this illness is affecting most everything and getting worse. I'm just at a loss for what I can possibly do. I've been seen by so many specialists that I can't even keep track of them! I saw a complex care doctor who said that this is a separate condition. However, he couldn't put a name on it. I feel like I have good doctors, though I have concerns about modern corporate medicine. I just want to be properly diagnosed with proper treatment options. Fistfuls of pills doesn't do anything for my underlying illness.