Could it be C.L.I.P.P.E.R.S.? Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is a very rare (< 0 documented cases to date) auto-immune disease that presents with multiple lesions in the brain. I was diagnosed with it at age 54 in spring of 2022 (last year) and after a course of high dose prednisone and follow ups with Rituxan infusions I have completely recovered. I was on pred from March-October but am currently on only Rituxience. My MRIs now show only gliosis (essentially scar tissue) but no more lesions. My symptoms were consistent with cranial nerve damage from the lesions: parathenia (numbness) in parts of my face/hands/leg, binocular diplopia (double vision-scary but kinda entertaining!), oscillopsia (vision jumps around - super unfun), gait imbalance (I still think this was due primarily to the vision issues) and...when things got bad, swallowing problems and a brief bout of rapid eye movement sleep behavior disorder (RBD) (that's a bad one, it indicates that the autonomic nervous system - breathing/heart rate is being impacted). A CLIPPERS diagnosis is one of exclusion, like the other comments note I was initially worked up for a ton of other things (brain tumor, MS, MG, neurosarcoidosis, CIDP, lymphoma and others) but we were able to rule all of those out. Have you been on pred yet? It's a fascinating drug as it does so much in your body (most not good) but it saved my life and I was able to manage the side effects (I now approach my fitness and health as training for a time in the future when I might have to have more treatment). I had hair thinning to, but I chalked that up to the prednisone. I certainly had a lot of fatigue but not your flu symptoms. It could be possible that you have a virus on top of the underlying disorder causing the lesions. Definitely talk to your doctor about CLIPPERS. Also keep in mind that the folks on this forum are often in acute phases or at their wit's end due to problems with treatments and diagnosis. People like me who got better tend to wander back to their daily lives so you don't see a lot of happy endings. But there are! Mine was terrifying but now I'm fine ... things can turn out okay! Here's a pic of me at my most recent Ruxience infusion (I get them every 6 months). My neurologist is planning to keep me on it two years total from when I first got sick...so two more to go.