Blood in poop. Help.

I noticed my month old boy had a small amount of blood in his poop. It was super small and 3 tiny spots and hasn’t happened before but I am a nervous FTM. I am going to call the pediatrician but their phone was not working earlier. Is this something I need to be super concerned about? This is the first time I have seen it. I am breastfeeding and pumping (only when I can’t be with him) and no formula. Anyone had this happen and what was the reason?