Period starting again 1 week later?!

I have been off my period for a week and I just started again.

It's not light like spotting it's literally like the beginning of a full blown period, symptoms and all.

My usual cycle is just over 31 days, give or take.

I'm sure it's nothing to worry about, just annoying but I wanted to know if this has happened to other women and if so, what was the cause?

I did think a few days ago I may have a yeast infection but the day before last it had gone. I also had my moped break down on the way to work and had a staff member down, and had a music performance the same day so I was pretty stressed... could that have affected it?