Period at 5 weeks pp?

Is it possible that I am having my period at 5 weeks postpartum? I never stopped bleeding. It just tapered off until there was barely anything then it was mucus for a few days. Now the blood has picked back up. It was light and reddish yesterday and today it is as heavy as my normal periods and a mix of brown and red. I am crampy, back hurts, tired,and grumpy so I'm pretty sure it is but when I mentioned it to my mom, she said there is no way I could after only 5 weeks. I am exclusively pumping by the way.