I've had a fever every day for over a month. At the beginning they were 101 and up, and my heart rate spiked over 100 for long periods of time (normally I'm in the 60's and 70's). Now the "fevers" are pretty low grade (under 100 but definitely higher than "normal.")

I'm also experiencing the crashes you mentioned - fine one minute and crawling back in bed the next. It's usually in the afternoons or evenings. But as you say, it's much better than before when I slept ALL DAY for several days.

To end on a brighter note, I am back to exercising 45 mins, 3 days a week. And I go biking weekends, for 1.5 - 2 hours. My stamina isn't what it was, but it's building back. I even decided to go ahead with a (virtual) race I signed up for. I'll walk/run with the only goal of finishing.