Hi, I Had My Period A Month Ago Around The

Hi,

I had my period a month ago around the 17th of April. I'm a few days late. However, today in the afternoon, I felt a little cramp. I realized then I had a little spotting. It is not heavy at all. It is very light blood such as a little paper cut blood amount. I've tested 4 pregnancy test and they all showed negative. However, when I got home in the evening, it stopped. What could be the problem?

Thank you.