Implantation bleeding?

Patient: I am on birth control and have been for 2 years and have always had a consistant period. howwver last night (3 days before i am supposed to get my period i had light red bleeding for about 4 hours then it went away and it has been EXTREMELY light today spotting. My bf used a condom when we had sex but i have been reading about my symptoms online and have read it could be implantation bleeding however we were both protected and the condom did not break.. what could this be?

Symptoms: LIGHT red bleeding