Period symptoms but no period?

So im on the pill, and my period was supposed to start sunday. My boyfriend did finished in me a day before i was supposed to start. Now its tuesday, still havent started. No symptoms until now, im having full blown cramps and just that “period feel” and all ive had was some brown spotting. Ive never had this happen before, im always on time and my periods are just very regular and consistent. Any ideas on whats going on? Thanks ✨