Help me please. Not really worried just really need some reassurance.

So today makes 8 weeks pregnant 😌 but for the past 5 days I've had brown spotting. Like some looked like brown CM then some days it looks like old blood etc. Is there a specific reason why I have this? I have some cramps in my lower back but I'm pretty sure its cause of the fact that we are moving . And I was lifting things for these 2 days