Spotting before my period what does it mean?

Hey everyone,

About 6 days ago I noticed some spotting (dark brown) and this lasted for 2 days. So in my mind I’m thinking I’m pregnant because my period was due in soon (glow predicted in 5 days) and I did some research and one of the results said it could possible be implantation bleeding since this happened near the time my period was due. I decided to take a pregnancy test and it came out negative. I did again after 2 more days and still negative. Then yesterday my period came on (on schedule). My period has always been on time and I’ve never experienced any spotting before my period in the past. Does anyone know what it could have been?

*P.S I am on birth control (pills) and have been for 3 years but last year I took a 2 month break from it and since then I’ve been on it.