Spotting - stress related?

Kirsty • 3rd pregnancy following a pprom loss at 16 weeks and a miscarriage at 6 weeks. Hoping this one is our rainbow 🌈

I’m currently cd13 (clearblue digital ovulation tests says low fertility- so not at ovulation). I usually ovulate around cd 18. I’ve had quite heavy spotting for two days now. It’s been happening more and more often throughout the past few cycles. Especially if I exercise heavily. Has anyone had this before? My doc told me before it could be stress related too?