Spotting but not pregnant. HELP

I have been on the pill since May and have only given myself a period once (in August) I’ve had really light bleeding for the past week but I’m not supposed to have a period for another 11 days. I took a pregnancy test but it was negative. I always take my pill at the same time everyday and have never missed one. I’m also super bloated and constipated. Any similar experiences or advice?