Birth control

So I’m new to this whole birth control stuff...on January 14 of this year I got on the shot and my last period was January 3 I was supposed to start my period sometime in February but February 7 I had unprotected sex I took a pregnancy test feb 10 and I took another one a couple of days later (I think it was feb 17 not sure ). But yesterday I was cramping on my lower stomach only on the right side so I found it kinda weird later on that day I noticed some light reddish blood on the toilet paper but as of now I only see a very faint red every time I wipe. I was wondering if it could be my birth control that’s messing up my period or what?