Spotting Question

Melody
So I had a miscarriage in April. My periods were irregular since. But this time I passed something that felt exactly like when I had my miscarriage but it was much smaller. I've been spotting since then. It's only been three days and it's just enough to mark up a panty liner over the course of a day. 
Here's my question: should I be concerned? I feel better than I have since my miscarriage. But I don't usually have spotting this long. I also started working out so maybe that has something to do with it?? What do you girls think??