It seems like it isn't uncommon to have lingering COVID-like symptoms after testing negative for the live culture, with varying degrees of severity [0][1][2].
Please leave your story if you've had similar symptoms. I'm especially interested in how you've been treating it and if you've had any success.
[0] https://www.wsj.com/articles/three-months-in-these-patients-are-still-ravaged-by-covids-fallout-11593612004
[1] https://www.sciencemag.org/news/2020/07/brain-fog-heart-damage-covid-19-s-lingering-problems-alarm-scientists
[2] https://www.statnews.com/2020/08/12/after-covid19-mental-neurological-effects-smolder/
I've pretty much experienced what lots of other people have related over the past 4-5 months--different symptoms popping up and going away every day, all falling into the kind of umbrella of post-viral symptoms.
I've definitely noticed a pretty big improvement the last few weeks but I still get hit out of the blue with fatigue, brain fog, and occasionally a heavy chest. I would be more concerned but I went through a very similar experience with mono a few years ago, and hoping things will continue to slowly lift with time and as u/notahacker mentioned rest, low intensity exercise, and healthy food.
All I've done are the generic health recommendations [sleep more, eat well, avoid alcohol, take regular low intensity exercise, avoid sources of stress]