mirena + working out

So I know spotting is normal with the IUD. But, I recently started working out again, and in the morning I wipe and there is no blood, I start working out (low intensity by the way) and I start spotting. I want and need to stay active, and I'm not even pushing myself. I just do 30 minutes on my stationary bycicle, squats, and lift 8 pound weights, so it really isn't that high impact. Also, I feel great while working out. I'm not even doing crunches. So, would it be ok if I keep working out like this or there is a potential harm?