Could I be pregnant?

Lydia

Hi friends—

I am ten days late for my period. Last night I was sure I was getting it, and when I wiped there was a little blood. So I put in a tampon and went to bed. I took out the tampon this morning, and nothing. Nothing all day today. I took a pregnancy test and it came back negative. I am cramping and feeling nauseous. So confused...any explanation?