Spotting been taking pill for a year

For the past 8 days I’ve had minimal spotting with mucus and have been taking the pill for over a year. Trying to figure out what it could be. I was on antibiotics for strep about 3 weeks ago. I’ve been on time with the pill everyday. Not sure if the pill has been working and that’s why I’m spotting. I also got pregnant on the pill and miscarried in January, so not sure if my hormones are still regulating and why I’m spotting. Any thoughts?