Not sure?

I had a miscarriage at 5w4d in July 29th. Only bled for four days. It’s now august 27th and I woke up to blood in the toilet and when I wiped and figured my period was starting but I put a tampon in and nothing when I checked it. We have had unprotected sex after my miscarriage bleeding stopped and I know I ovulated august 13th. Not sure what the bleeding is and I have lower back pain. pregnancy still possible?