Early onset muscle fatigue

Hi All,

Just looking to see if anyone else has had experience with what I’m getting at the moment. Last week I got a really mild stomach bug that caused nausea and diarrhea. That completely eased after a couple of days and I now feel completely fine. Except that now whenever I try to do any sort of intensity on the bike my legs just feel completely dead, like I’ve already done an hour of intervals when I’m only a minute into my first one. I haven’t done a proper ride for 10 days now so should be really fresh but I feel like I’m in the third week of a grand tour when trying to ride.
I’d usually put it down to normal post-sickness symptoms but just seems strange that I feel other wise well.
Just wondering if anyone else has experienced this and how long it took to subside.