My boyfriend and I had normal sex on Saturday night on Sunday morning I got up and was walking to the bathroom when I all of a sudden felt like someone kick me in the stomach when I ran to the bathroom my panties were full of bright red blood so I cleaned up and did my thing later that day when I went to the bathroom all the bleeding had stopped and I haven't bled since then this is a day before my period was due but I never got a full period what does it mean...

Sometimes sex near a period may throw it off a bit. See if your period starts up in the next few days.