5 Days Brown Spotting

I've had 5 days of nothing but light brown spotting. pregnancy tests all say negative. No pink or red streaks, just brown- mostly when I wipe. I also had 2 days of brown spotting the cycle before this one.

My flow has been really heavy since baby #2 and I get a lot of pelvic floor pain on day 1 of my period (red flow).

Hubby and I are trying for baby #3, but this has me worried. I'm making a Dr appt, but I was wondering if anyone has experienced anything like this??