For starters, I would do nothing different except work less hard (lower resistance and/or lower cadence). If the seat height worked for you before, then it's probably still okay.

I've noticed sometimes while doing some kind of cardio exercise that I get a pain in my knee or foot or whatever, so I dial way back on the intensity and stop the exercise altogether if it doesn't feel better. Then I try again a few days later, and sometimes the pain is not there. So either the pain was caused by doing too much too soon, or it was just one of those days when things weren't lined up right.