Sorry you've gotten hit with the long covid symptoms. The fatigue can be brutal. Additional covid vaccinations / boosters can re-trigger it, so proceed with caution. Trying to do any amount of endurance-style exercise, especially running, can cause post-exertional malaise.
I was a long-distance triathlete prior to covid with 20+ years of endurance sports history. I had covid at the very start of the pandemic. It was a mild-feeling infection, but then I never got better from the burning lungs and other symptoms and started getting hit with a bunch others after a few months. It's been since March of 2020, and my lungs burn to this day, coughing, fatigue up and down, many of the long-hauler symptoms you'll read about. I kept trying to ease back into some light exercise, but every time would suffer big setbacks after a few minimal, short sessions of nothing-level efforts.
Best advice I can give you is to rest until you have no more symptoms, then rest some more. Don't try starting up any running again until you are completely well. Go easy and just let your body recover. Do some modest amounts of easy walking if you're up to it, but don't push things beyond that if you still have symptoms. Hope you get better.