4w1d chemical??

Hi all! So, I found out Monday we were expecting. I was in total shake because I started spotting at 8dpo on Thursday last week. Ran 18 miles Saturday and my uterus was so tight and hurt the last 6 miles. Stopped spotting on Sunday and then BFP Monday! BUT I started spotting brown yesterday again 😭 cramps too. Nothing in a pad, only when I wipe. Is this normal?? My doctor wanted me to wait until I missed my period which is passed (I’m 28 days) and never called me back yesterday. Is this a chemical or miscarriage? I’ve taken a test each day and the line keeps getting darker. Just concerned!