Rectal bleeding.

It's been around 2 week's since I notice that I would bleed every time i had a bowl movement and every time it hurts real bad to go and I've been having lower back and abdomen pain, I didn't think anything about it cuz I though that the bleeding was probably cuz my bowl movement's we're to thick and I thought my back and abdomen pain was cuz i was probably getting my period,

But today when I went it really hurt and when I wiped there were blood clots and the toilet was bright red 'im sure its not my period' that really got me scared, im going to make an appointment with my doctor on Monday, but I was just wondering if this has happened to any of you? And what was it? Thank's in advance