Period a week after Having Intercourse? Spotting??

I got my period September 3rd and then I had sexual intercourse on the 26th of Sept with my partner. I got light red/pink bleeding on the 3rd of October. But the bleeding wasn’t normal. It was like blood, with spots like with my firstborn! But what I don’t understand is if I am pregnant, how can this be because  I had intercourse about 2 1/2 weeks from the first day of my period?! I feel light cramps and I urinate often and my lower abdomen feels sore and a little hard?
HAS ANYONE ENCOUNTERED THIS BEFORE?

Another thing is when I was pregnant with my daughter, my baby father slept a lot and now he is doing the same!! Am I?? I am going to the doctor’s to take a test but I feel that I am. I also have slight back pain (cramps) which I felt with my first child. I don’t know.

Please someone tell me that this has happened to them before! Is It Normal??