I wish I had a clue, Machka, but I don't.

Whenever I come back from an injury, I try to ride every day, gently. Very gently. No pain, or at least very little. And I just gently ramp up the volume first, then try to get back to more normal effort. I would think that if your weekly volume were up around 8 hours for a month, a metric would go OK. I'd further guess that all that standing has tired you out more than you realize.

Do keep the effort down when you bike until that clot is gone. We know you love to bike but please don't endanger yourself.

More guessing: the cramping was just because you weren't in shape for it. Too big a bump. Give it time. The older we get, the faster we lose it. It's noticeable. OTOH, the cramping might have had something to do with reduced blood flow, but then I would think it would have been localized to the affected muscles.