Covid, hypothalamus, lesions

I just typed all this in a forum so I’m just copying and pasting…

My husband was diagnosed in 2013. He’s never really had relapses - just a slow decline that will plateau and then decline again. Doctors still say that he has relapsing remitting but we are both confident that he has secondary progressive. Most of his lesions are in his spinal cord instead of the brain. He has been on Rituximaub therapy for 5 years now.
We both managed to make it until Thanksgiving of 2022 without getting Covid. I recovered in a week. My husband on the other hand is another story. He was admitted to the hospital a few days after getting sick - cough, low O2 levels, high fever, elevated heart rate. After getting 2 doses of Remdesivir and 4 days in the hospital, things got better and he was discharged. After just a few days, his fever was back. I’m sure I don’t have to tell you all how miserable he is with even the slightest fever. He still had a cough but it was productive and his O2 was normal so we tried treating at home with cough meds and Tylenol for the fever. After a week, the fevers were worse and heart rate was still high so back to the ER we go. They find he has a bladder infection and so antibiotics are prescribed and he’s sent home. UTI cleared up, he finished his round of antibiotics, but the fevers and fast heart rate continued. We continue to try the treat at home with no luck. Back to the ER for the 3rd time in a month. He’s admitted again while they run a battery of tests. They don’t believe that the fevers are connected to Covid this far out. By this time he has no cough at all and O2 is normal. Blood work is all normal, blood cultures grow absolutely nothing, CT scans, show nothing, chest X-ray shows a little cloudiness in lungs but that’s dismissed as scarring from the Covid. They start 2 Antibiotics by IV, Meropenem and Vancomycin (both very strong broad spectrum drugs that should kill absolutely any bacteria in his body). They continue to run blood work and blood cultures. Nothing changes. Then comes the nausea. So now his symptoms are daily fevers, fast heart rate, and nausea. They send him to a larger hospital for a PET scan that still provides no answers. Out of options, they treat him for Covid again - maybe his immune system just can’t kick what little bit is left out. This time, it’s 5 days of Remdesivir. By the last dose, he’s feeling better. Temp is staying normal, nausea has subsided, HR is still a little high but nothing like it was. So after 13 days in this hospital, he is sent home. 4 days later, the fevers start back. He’s been home since January 17th. The fevers started back that weekend. He has ran a fever every day since. Nausea comes and goes, diarrhea every now and then, heart rate is still crazy (anywhere from 109 - the lowest it’s been in 2 weeks, to 154).
Doctors don’t have any answers. We’ve seen his neurologist, primary care, internist, and even infectious disease.
Here are my questions:
Has anyone experienced anything like this following Covid or any kind of illness?
Is it possible that Covid triggered and masked an exacerbation causing a lesion on his hypothalamus? (The part of the brain that regulates body temp, heart rate, sleep cycle, and gastrointestinal issues)
Does anyone have a lesion on their hypothalamus and if so, what issues does it cause you?
Thanks for bearing with me. We are both exhausted and so frustrated at this point. We just want answers and for him to feel better.