Can doing too much cause bleeding?

Hi, I did a fundraising walk with my class today and walked around 3 mile, then was teaching the rest of my day on my feet, as you can imagine I was shattered! Anyway around 4pm I started bleeding and it was bright red. I managed to get an appointment at the hospital and they said the baby seems fine and my cervix is closed, and they can’t pinpoint why I was bleeding and just told me to rest.

Could the bleeding me from doing too much today? Or is it just random? I’m worried now that I’m doing too much at work! I have an appointment with my midwife next week so will discuss it with her then but just want to hear others opinions xxx