is this af or pregnancy?

Alexis • Mom of a little girl ❤️ Aubree Elizabeth Dellinger was born 9/1/28
I should of started my af yesterday but instead I had brown discharge (old blood). Today I'm having the same thing. It has only hit my pad once today and 1 time yesterday. I'm having no cramps right now but earlier I had light cramps and my left hip was hurting. Is this my af or pregnancy