What Causes Bleeding And Spotting?

Hi There my girlfriend started to bleed red yesterday from noon and it settled down around 630 pm with light spotting. The bleeding was not heavy but had cramping involved as well. She had a really stressful day and did do a lot of house work. Now that she is not spotting or bleeding is everything ok. We had her take the day off of work as well today to rest and enjoy girl time.