You say decline started around March of 21 which would have been after the vaccine.. Your time line is very much like mine. I had covid March 2020 but started having "issues" maybe 3 weeks after getting vaccinated in Feb 2021. I use the vaccine date as reference only because i serves to provide a timeline and so many of my symptoms, numbness/tingling, ears ringing, what feels like inflammation of bronchial passages and in my jaw. are so similar to long covid. I mean they are unique and all tests came up negative but stared to occur over a yr. after having covid and not immediately after getting vaccinated. Then I had an episode where I saw flashes of light and half of the room went dark. It was no my eyes and I was checked for stroke and nothing. It's just that the symptoms are so different and all tests negative. Think covid can exacerbate or activate other issues. Given you had issues before covid, I'd try to work with a specialist/doc that can work with you while you go through a long covid clinic. Good luck.